Low Latency 40-Gbps Ethernet IP Core User Guide

RSS

UG-20043 | 2020.09.04

Version Information

Updated for:
Intel® Quartus® Prime Design Suite 16.1

1. About the LL 40GbE IP Core

The Intel^® Low Latency 40 -Gbps Ethernet (LL 40GbE) media access controller (MAC) and PHY Intel^® FPGA IP functions offer the lowest round-trip latency and smallest size to implement the IEEE 802.3ba High Speed Ethernet Standard with an option to support the IEEE 802.3ap-2007 Backplane Ethernet Standard.

The version of this product that supports Intel^® Arria^® 10 devices is included in the Intel FPGA IP Library and is available from the Intel^® Quartus^® Prime IP Catalog.

Note: The full product name, Low Latency 40 -Gbps Ethernet MAC and PHY Intel^® FPGA IP Function, is shortened to Low Latency (LL) 40 GbE (LL 40GbE) IP core in this document. In addition, although multiple variations are available from the parameter editor, this document refers to this product as a single IP core, because all variations are configurable from the same parameter editor.

Figure 1. LL 40GbE IP CoreMain blocks, internal connections, and external block requirements.

As illustrated, on the MAC client side you can choose a wide, standard Avalon^® streaming interface (Avalon-ST), or a narrower, custom streaming interface. The MAC client side Avalon^® streaming interface data bus is 256 bits wide. The MAC client side custom streaming interface data bus is 127 bits wide. The client-side data maps to four 10.3125 Gbps transceiver PHY links.

The 40GbE (XLAUI) interface has 4x10.3125 Gbps links. For Intel^® Arria^® 10 devices only, you can configure a 40GbE 40GBASE-KR4 variation to support Backplane Ethernet.

The FPGA serial transceivers are compliant with the IEEE 802.3ba standard XLAUI specification . You can connect the transceiver interfaces directly to an external physical medium dependent (PMD) optical module or to another device.

The IP core provides standard MAC and physical coding sublayer (PCS) functions with a variety of configuration and status registers. You can exclude the statistics registers. If you exclude these registers, you can monitor the statistics counter increment vectors that the IP core provides at the client side interface and maintain your own counters.

1.1. LL 40GbE IP Core Supported Features

All LL 40GbE IP core variations include both a MAC and a PHY, and all variations are in full-duplex mode. These IP core variations offer the following features:

Designed to the IEEE 802.3ba-2010 High Speed Ethernet Standard available on the IEEE website (www.ieee.org).
Soft PCS logic that interfaces seamlessly to Intel FPGA 10.3125 Gbps serial transceivers.
Standard XLAUI external interface consisting of four FPGA hard serial transceiver lanes operating at 10.3125 Gbps.
Supports 40GBASE-KR4 PHY based on 64B/66B encoding with data striping and alignment markers to align data from multiple lanes.
Supports 40GBASE-KR4 PHY and forward error correction (FEC) option for interfacing to backplanes. The supported FEC is KR-FEC.
Supports Synchronous Ethernet (SyncE) by providing an optional CDR recovered clock output signal to the device fabric.
Avalon^® memory mapped (Avalon-MM) management interface to access the IP core control and status registers.
Avalon^® streaming (Avalon-ST) data path interface connects to client logic with the start of frame in the most significant byte (MSB) when optional adapters are used. Interface has data width 256 bits.
Optional custom streaming data path interface with narrower bus width and a start frame possible on 64‑bit word boundaries without the optional adapters. Interface has data width 128 bits.
Support for jumbo packets.
TX and RX CRC pass-through control.
Optional TX CRC generation and insertion.
RX CRC checking and error reporting.
TX error insertion capability supports test and debug.
RX and TX preamble pass-through options for applications that require proprietary user management information transfer.
TX automatic frame padding to meet the 64-byte minimum Ethernet frame length at the LL 40GbE Ethernet connection.
Optional RX strict SFD checking per IEEE specification.
RX malformed packet checking per IEEE specification.
Hardware and software reset control.
Pause frame filtering control.
Received control frame type indication.
MAC provides cut-through frame processing.
Optional deficit idle counter (DIC) options to maintain a finely controlled 8-byte or 12-byte inter-packet gap (IPG) minimum average.
Optional IEEE 802.3 Clause 31 Ethernet flow control operation using the pause registers or pause interface.
Optional priority-based flow control that complies with the IEEE Standard 802.1Qbb-2011—Amendment 17: Priority-based Flow Control, using the pause registers for fine control.
1900 bits RX PCS lane skew tolerance, which exceeds the IEEE 802.3-2012 Ethernet standard clause 82.2.12 requirements.
Optional support for the IEEE Standard 1588-2008 Precision Clock Synchronization Protocol (1588 PTP).
Optional statistics counters.
Optional fault signaling: detects and reports local fault and generates remote fault, with IEEE 802.3ba-2012 Ethernet Standard Clause 66 support.
Optional serial PMA loopback (TX to RX) at the serial transceiver for self-diagnostic testing.
Optional access to Native PHY Debug Master Endpoint (NPDME) for debugging or monitoring PHY signal integrity.

The LL 40GbE IP core can support full wire line speed with a 64-byte frame length and back-to-back or mixed length traffic with no dropped packets.

For a detailed specification of the Ethernet protocol refer to the IEEE 802.3ba-2010 High Speed Ethernet Standard.

1.2. IP Core Device Family and Speed Grade Support

The following sections list the device family and device speed grade support offered by the Low Latency 40-Gbps Ethernet Intel FPGA IP:

1.2.1. LL 40GbE IP Core Device Family Support

Table 1. Intel FPGA IP Core Device Support Levels
Device Support Level	Definition
Preliminary	The IP core is verified with preliminary timing models for this device family. The IP core meets all functional requirements, but might still be undergoing timing analysis for the device family. It can be used in production designs with caution.
Final	The IP core is verified with final timing models for this device family. The IP core meets all functional and timing requirements for the device family and can be used in production designs.

Table 2. LL 40GbE IP Core Device Family SupportShows the level of support offered by the LL 40GbE IP core for each Intel FPGA device family.
Device Family	Support
Stratix^® V (GX, GT, and GS)	Final
Arria 10 (GX, GT, and SX)	Default support level provided in the Intel^® Quartus^® Prime software. Refer to the Quartus Prime Standard Edition Software and Device Support Release Notes and the Quartus Prime Pro Edition Software and Device Support Release Notes.
Other device families	Not supported

1.2.2. LL 40GbE IP Core Device Speed Grade Support

Table 3. Slowest Supported Device Speed GradesLists the slowest supported device speed grades for standard variations of the LL 40GbE IP core. IP core variations that include a 1588 PTP module might require Intel^® Quartus^® Prime seed sweeping to achieve a comfortable timing margin.
Intel^® FPGA IP Function	Device Family	Supported Speed Grades
LL 40GbE	Stratix V (GX)	I3, C3
	Stratix V (GT)	I3, C2
	Stratix V (GS)	I3, C3
	Arria 10 (GX, GT, SX)	I2, C2
LL 40GbE (40GBASE-KR4 option)	Arria 10 (GX, GT, SX)	I2, C2

1.3. IP Core Verification

To ensure functional correctness of the LL 40GbE IP core, Intel performs extensive validation through both simulation and hardware testing. Before releasing a version of the LL 40GbE IP core, Intel runs comprehensive regression tests in the current or associated version of the Intel^® Quartus^® Prime software.

Intel verifies that the current version of the Intel^® Quartus^® Prime software compiles the previous version of each IP core. Any exceptions to this verification are reported in the Intel FPGA IP Release Notes. Intel does not verify compilation with IP core versions older than the previous release.

1.3.1. Simulation Environment

Intel performs the following tests on the LL 40GbE IP core in the simulation environment using internal and third party standard bus functional models (BFM):

Constrained random tests that cover randomized frame size and contents
Randomized error injection tests that inject Frame Check Sequence (FCS) field errors, runt packets, and corrupt control characters, and then check for the proper response from the IP core
Assertion based tests to confirm proper behavior of the IP core with respect to the specification
Extensive coverage of our runtime configuration space and proper behavior in all possible modes of operation

1.3.2. Compilation Checking

Intel performs compilation testing on an extensive set of LL 40GbE IP core variations and designs that target different devices, to ensure the Intel^® Quartus^® Prime software places and routes the IP core ports correctly.

1.3.3. Hardware Testing

Intel performs hardware testing of the key functions of the LL 40GbE IP core using standard 40 Gbps Ethernet network test equipment and optical modules. The Intel hardware tests of the LL 40GbE IP core also ensure reliable solution coverage for hardware related areas such as performance, link synchronization, and reset recovery.

1.4. Performance and Resource Utilization

The following sections provide performance and resource utilization data for the LL 40GbE IP core.

Table 4. IP Core Variation Encoding for Resource Utilization Tables"On" indicates the parameter is turned on. The symbol "—" indicates the parameter is turned off or not available.
IP Core Variation	A	B	C	D	E	F
Parameter	A	B	C	D	E	F
Data interface	Custom-ST	Avalon-ST	Avalon-ST	Avalon-ST	Avalon-ST	Avalon-ST
Flow control mode	No flow control	No flow control	Standard flow control	Standard flow control	No flow control	No flow control
Average interpacket gap	12	12	12	12	12	12
Enable 1588 PTP	—	—	—	On	—	—
Enable link fault generation	—	—	On	On	—	—
Enable TX CRC insertion	—	On	On	On	On	On
Enable preamble passthrough	—	—	On	On	—	—
Enable alignment EOP on FCS word	—	On	On	On	On	On
Enable TX statistics	—	On	On	On	On	On
Enable RX statistics	—	On	On	On	On	On
Enable KR4	—	—	—	—	On	On
Include FEC sublayer	—	—	—	—	—	On

1.4.1. Arria 10 Resource Utilization

Resource utilization changes depending on the parameter settings you specify in the LL 40GbE parameter editor. For example, if you turn on pause functionality or statistics counters in the LL 40GbE parameter editor, the IP core requires additional resources to implement the additional functionality.

Table 5. IP Core FPGA Resource Utilization in Arria 10 Devices Lists the resources and expected performance for selected variations of the LL 40GbE IP core in an Arria 10 device.
These results were obtained using the Intel^® Quartus^® Prime software v14.1 .

The numbers of ALMs and logic registers are rounded up to the nearest 100.

The numbers of ALMs, before rounding, are the **ALMs needed** numbers from the Intel^® Quartus^® Prime Fitter Report.
LL 40GbE Variation	ALMs	Dedicated Logic Registers	Memory M20K
LL 40GbE variation A	5400	12800	13
LL 40GbE variation B	10100	21200	13
LL 40GbE variation C	11000	24100	13
LL 40GbE variation D	14200	31100	17
LL 40GbE variation E	14400	28200	26
LL 40GbE variation F	16300	29300	26

1.4.2. Stratix V Resource Utilization

Table 6. IP Core FPGA Resource Utilization in Stratix V Devices Lists the resources and expected performance for selected variations of the LL 40GbE IP core in a Stratix V device.
These results were obtained using the Quartus II software v14.1.

Note: Please note that at the time of publication, the LL 40GbE IP core that targets a Stratix V device has not been updated since the version compatible with the Intel^® Quartus^® Prime Standard Edition software v16.0.

The numbers of ALMs and logic registers are rounded up to the nearest 100.

The numbers of ALMs, before rounding, are the **ALMs needed** numbers from the Intel^® Quartus^® Prime Fitter Report.
40GbE Variation	ALMs	Dedicated Logic Registers	Memory M20K
40GbE variation A	5300	12800	13
40GbE variation B	9900	21500	13
40GbE variation C	10900	24100	13
40GbE variation D	14000	31000	17

1.5. Release Information

Table 7. LL 40GbE IP Core Current Release Information
Item	Description
Version	16.1
Release Date	2016.10.31
Ordering Codes	Low Latency 40G Ethernet MAC and PHY: IP-40GEUMACPHY Low Latency 40G Ethernet MAC and PHY with 1588: IP-40GEUMACPHYF Low Latency 40G Ethernet MAC and 40GBASE-KR4 PHY with FEC: IP-40GBASEKR4PHY
Vendor ID	6AF7

2. Getting Started

The following sections explain how to install, parameterize, simulate, and initialize the LL 40GbE IP core:

2.1. Installation and Licensing for LL 40GbE IP Core for Stratix V Devices

The LL 40GbE IP core that targets the Stratix^® V device family is an extended IP core which is not included with the Intel^® Quartus^® Prime release. This section provides a general overview of the Intel extended FPGA IP core installation process to help you quickly get started with any Intel extended FPGA IP core.

The Intel extended FPGA IP cores are available from the Self-Service Licensing Center (SSLC). Refer to Related Links below for the correct link for this IP core.

Figure 2. IP Core Directory Structure Directory structure after you install the LL 40GbE IP core that targets a Stratix^® V device.

Note: At the time of publication, the most recent Stratix^® V LL 40GbE IP core available from the SSLC is a combined Low Latency 40-100GbE IP core compatible with the Intel^® Quartus^® Prime Standard Edition software v16.0.

Table 8. Default Intel^® Quartus^® Prime Standard Edition Installation LocationsLists the default location of <`path`>. The Stratix^® V LL 40GbE IP core available in the SSLC at the time of publication is compatible with the Intel^® Quartus^® Prime Standard Edition software v16.0.
Default Location in 16.1 Release	Default Location in 16.0 Release	Platform
`<drive>`:\intelFPGA\quartus\`<version number>`\	`<drive>`:\altera\quartus\`<version number>`\	Windows
`<home directory>`:/intelFPGA/quartus/`<version number>`	`<home directory>`:/opt/altera/quartus/`<version number>`	Linux

You can evaluate an IP core in simulation and in hardware until you are satisfied with its functionality and performance. You must purchase a license for the IP core when you want to take your design to production. After you purchase a license for an Intel FPGA IP core, you can request a license file from the Licensing page of the Intel website and install the license on your computer.

2.2. Installing and Licensing Intel FPGA IP Cores

The Intel^® Quartus^® Prime software installation includes the Intel^® FPGA IP library. This library provides many useful IP cores for your production use without the need for an additional license. Some Intel^® FPGA IP cores require purchase of a separate license for production use. The Intel^® FPGA IP Evaluation Mode allows you to evaluate these licensed Intel^® FPGA IP cores in simulation and hardware, before deciding to purchase a full production IP core license. You only need to purchase a full production license for licensed Intel^® IP cores after you complete hardware testing and are ready to use the IP in production.

The Intel^® Quartus^® Prime software installs IP cores in the following locations by default:

Figure 3. IP Core Installation Path

Table 9. IP Core Installation Locations
Location	Software	Platform
`<drive>`:\intelFPGA_pro\quartus\ip\altera	Intel^® Quartus^® Prime Pro Edition	Windows*
`<drive>`:\intelFPGA\quartus\ip\altera	Intel^® Quartus^® Prime Standard Edition	Windows
`<home directory>`:/intelFPGA_pro/quartus/ip/altera	Intel^® Quartus^® Prime Pro Edition	Linux*
`<home directory>`:/intelFPGA/quartus/ip/altera	Intel^® Quartus^® Prime Standard Edition	Linux

Note: The Intel^® Quartus^® Prime software does not support spaces in the installation path.

2.2.1. Intel FPGA IP Evaluation Mode

The free Intel^® FPGA IP Evaluation Mode allows you to evaluate licensed Intel^® FPGA IP cores in simulation and hardware before purchase. Intel^® FPGA IP Evaluation Mode supports the following evaluations without additional license:

Simulate the behavior of a licensed Intel^® FPGA IP core in your system.
Verify the functionality, size, and speed of the IP core quickly and easily.
Generate time-limited device programming files for designs that include IP cores.
Program a device with your IP core and verify your design in hardware.

Intel^® FPGA IP Evaluation Mode supports the following operation modes:

Tethered—Allows running the design containing the licensed Intel^® FPGA IP indefinitely with a connection between your board and the host computer. Tethered mode requires a serial joint test action group (JTAG) cable connected between the JTAG port on your board and the host computer, which is running the Intel^® Quartus^® Prime Programmer for the duration of the hardware evaluation period. The Programmer only requires a minimum installation of the Intel^® Quartus^® Prime software, and requires no Intel^® Quartus^® Prime license. The host computer controls the evaluation time by sending a periodic signal to the device via the JTAG port. If all licensed IP cores in the design support tethered mode, the evaluation time runs until any IP core evaluation expires. If all of the IP cores support unlimited evaluation time, the device does not time-out.
Untethered—Allows running the design containing the licensed IP for a limited time. The IP core reverts to untethered mode if the device disconnects from the host computer running the Intel^® Quartus^® Prime software. The IP core also reverts to untethered mode if any other licensed IP core in the design does not support tethered mode.

When the evaluation time expires for any licensed Intel^® FPGA IP in the design, the design stops functioning. All IP cores that use the Intel^® FPGA IP Evaluation Mode time out simultaneously when any IP core in the design times out. When the evaluation time expires, you must reprogram the FPGA device before continuing hardware verification. To extend use of the IP core for production, purchase a full production license for the IP core.

You must purchase the license and generate a full production license key before you can generate an unrestricted device programming file. During Intel^® FPGA IP Evaluation Mode, the Compiler only generates a time-limited device programming file (<project name> _time_limited.sof) that expires at the time limit.

Figure 4. Intel^® FPGA IP Evaluation Mode Flow

Note: Refer to each IP core's user guide for parameterization steps and implementation details.

Intel^® licenses IP cores on a per-seat, perpetual basis. The license fee includes first-year maintenance and support. You must renew the maintenance contract to receive updates, bug fixes, and technical support beyond the first year. You must purchase a full production license for Intel^® FPGA IP cores that require a production license, before generating programming files that you may use for an unlimited time. During Intel^® FPGA IP Evaluation Mode, the Compiler only generates a time-limited device programming file (<project name> _time_limited.sof) that expires at the time limit. To obtain your production license keys, visit the Self-Service Licensing Center.

The Intel^® FPGA Software License Agreements govern the installation and use of licensed IP cores, the Intel^® Quartus^® Prime design software, and all unlicensed IP cores.

2.3. Specifying the IP Core Parameters and Options

The LL 40GbE parameter editor allows you to quickly configure your custom IP variation. Use the following steps to specify IP core options and parameters in the Quartus Prime software.

In the IP Catalog (Tools > IP Catalog), select a target device family. The LL 40GbE IP core is not supported in Platform Designer (Standard).
In the IP Catalog, locate and double-click the name of the IP core to customize ( Low Latency 40G Ethernet). The New IP Variation window appears.
Specify a top-level name for your custom IP variation. The parameter editor saves the IP variation settings in a file with one of the following names:
- <your_ip> .qsys (for Arria 10 variations generated in the Intel^® Quartus^® Prime Standard Edition software)
- <your_ip> .ip (for Arria 10 variations generated in the Intel^® Quartus^® Prime Pro Edition software)
- <your_ip> .qip (for Stratix V variations)
If your IP core targets the Arria 10 device family, you must select a specific device in the Device field or maintain the default device the Quartus Prime software lists. If you target a specific Intel development kit, the hardware design example overwrites the selection with the device on the target board.
Click OK. The parameter editor appears.
Specify the parameters and options for your IP variation in the parameter editor, including one or more of the following. Refer to your IP core user guide for information about specific IP core parameters.
- Specify parameters defining the IP core functionality, port configurations, and device-specific features.
- Specify options for processing the IP core files in other EDA tools.
- A functional VHDL IP core is not available. Specify Verilog HDL only, for your IP core variation.
For Arria 10 variations, follow these steps:
1. Optionally, to generate a simulation testbench or example project, follow the instructions in Generating the LL 40GbE Testbench.
2. Click Generate HDL. The Generation dialog box appears.
3. Specify output file generation options, and then click Generate. The IP variation files generate according to your specifications.
4. Click Finish. The parameter editor adds the top-level .qsys file to the current project automatically. If you are prompted to manually add the .qsys or .ip file to the project, click Project > Add/Remove Files in Project to add the file.
For Stratix V variations, follow these steps:
1. Click Finish.
2. Optionally, to generate a simulation testbench or example project, follow the instructions in Generating the LL 40GbE Testbench.
  After you click Finish and optionally follow the additional step to generate a simulation testbench and example project, if available for your IP core variation, the parameter editor adds the top-level .qip file to the current project automatically. If you are prompted to manually add this file to the project, click Project > Add/Remove Files in Project to add the file.
After generating and instantiating your IP variation, make appropriate pin assignments to connect ports.

2.4. IP Core Parameters

The LL 40GbE parameter editor provides the parameters you can set to configure the LL 40GbE IP core and simulation and hardware design examples.

LL 40GbE IP core variations that target an Arria 10 device include an Example Design tab. For information about that tab, refer to the Low Latency 40G Ethernet Design Example User Guide.

Table 10. LL 40GbE Parameters: Main TabDescribes the parameters for customizing the LL 40GbE IP core on the Main tab of the LL 40GbE parameter editor.
Parameter	Type	Range	Default Setting	Parameter Description
General Options
Device family	String	Stratix V Arria 10	According to the setting in the project or IP Catalog settings.	Selects the device family.
Data interface	String	Custom–ST Avalon–ST	Avalon–ST	Selects the Avalon^® streaming interface or the narrower, custom streaming client interface to the MAC. If you select the custom streaming client interface, the Flow control mode and Enable 1588 PTP parameters are not available.
PCS/PMA Options
Enable SyncE	Boolean	True False	False	Exposes the RX recovered clock as an output signal. This feature supports the Synchronous Ethernet standard described in the ITU-T G.8261, G.8262, and G.8264 recommendations. This parameter is available only in variations that target an Arria 10 device.
PHY reference frequency	Integer (encoding)	322.265625 MHz 644.53125 MHz	644.53125 MHz	Sets the expected incoming PHY `clk_ref` reference frequency. The input clock frequency must match the frequency you specify for this parameter (± 100ppm).
Use external TX MAC PLL	Boolean	True False	False	If you turn this option on, the IP core is configured to expect an input clock to drive the TX MAC. The input clock signal is `clk_txmac_in`.
Flow Control Options
Flow control mode	String	No flow control Standard flow control Priority-based flow control	No flow control	Configures the flow control mechanism the IP core implements. Standard flow control is Ethernet standard flow control. If you select the custom streaming client interface, the IP core must be configured with no flow control, and this parameter is not available.
Number of PFC queues	Integer	1–8	8	Number of distinct priority queues for priority-based flow control. This parameter is available only if you set Flow control mode to Priority-based flow control.
Average interpacket gap	String	Disable deficit idle counter 8 12	12	If you set the value of this parameter to 8 or to 12, the IP core includes a deficit idle counter (DIC), which maintains an average interpacket gap (IPG) of 8 or 12, as you specify. If you set the value of this parameter to Disable deficit idle counter, the IP core is configured without the DIC, and does not maintain the required minimum average IPG. The Ethernet standard requires a minimum average IPG of 12. Turning off the DIC increases bandwidth.
MAC Options
Enable 1588 PTP	Boolean	True False	False	If turned on, the IP core supports the IEEE Standard 1588-2008 Precision Clock Synchronization Protocol, by providing the hooks to implement the Precise Timing Protocol (PTP). If you select the custom streaming client interface, the IP core must be configured without 1588 support, and this parameter is not available.
Enable 96b Time of Day Format	Boolean	True False	True	Include the 96-bit interface to the TOD module. If you turn on this parameter, the TOD module that is generated with the IP core has a matching 96-bit timestamp interface. If Enable 1588 PTP is turned on, you must turn on at least one of Enable 96b Time of Day Format and Enable 64b Time of Day Format. You can turn on both Enable 96b Time of Day Format and Enable 64b Time of Day Format to generate a TOD interface for each format. This parameter is available only in variations with Enable 1588 PTP turned on.
Enable 64b Time of Day Format	Boolean	True False	False	Include the 64-bit interface to the TOD module. If you turn on this parameter, the TOD module that is generated with the IP core has a matching 64-bit timestamp interface. If Enable 1588 PTP is turned on, you must turn on at least one of Enable 96b Time of Day Format and Enable 64b Time of Day Format. You can turn on both Enable 96b Time of Day Format and Enable 64b Time of Day Format to generate a TOD interface for each format. This parameter is available only in variations with Enable 1588 PTP turned on.
Timestamp fingerprint width	Integer	1–16	1	Specifies the number of bits in the fingerprint that the IP core handles. This parameter is available only in variations with Enable 1588 PTP turned on.
Enable link fault generation	Boolean	True False	False	If turned on, the IP core includes the link fault signaling modules and relevant signals. If turned off, the IP core is configured without these modules and without these signals. Turning on link fault signaling provides your design a tool to improve reliability, but increases resource utilization.
Enable TX CRC insertion	Boolean	True False	True	If turned on, the IP core inserts a 32-bit Frame Check Sequence (FCS), which is a CRC-32 checksum, in outgoing Ethernet frames. If turned off, the IP core does not insert the CRC-32 sequence in outgoing Ethernet communication. Turning on TX CRC insertion improves reliability but increases resource utilization and latency through the IP core. If you turn on flow control, the IP core must be configured with TX CRC insertion, and this parameter is not available.
Enable preamble passthrough	Boolean	True False	False	If turned on, the IP core is in RX and TX preamble pass-through mode. In RX preamble pass-through mode, the IP core passes the preamble and SFD to the client instead of stripping them out of the Ethernet packet. In TX preamble pass-through mode, the client specifies the preamble to be sent in the Ethernet frame.
Enable alignment EOP on FCS word	Boolean	True False	True	If turned on, the IP core aligns the 32-bit Frame Check Sequence (FCS) error signal with the assertion of the EOP by delaying the RX data bus to match the latency of the FCS computation. If turned off, the IP core does not delay the RX data bus to match the latency of the FCS computation. If the parameter is turned off, the FCS error signal, in the case of an FCS error, is asserted in a later clock cycle than the relevant assertion of the EOP signal. Intel recommends that you turn on this option. Otherwise, the latency between the EOP indication and assertion of the FCS error signal is non-deterministic. You must turn on this parameter if your design relies on the `rx_inc_octetsOK` signal..
Enable TX statistics	Boolean	True False	True	If turned on, the IP core includes built–in TX statistics counters. If turned off, the IP core is configured without TX statistics counters. In any case, the IP core is configured with TX statistics counter increment output vectors.
Enable RX statistics	Boolean	True False	True	If turned on, the IP core includes built–in RX statistics counters. If turned off, the IP core is configured without RX statistics counters. In any case, the IP core is configured with RX statistics counter increment output vectors.
Enable strict SFD checking	Boolean	True False	False	If turned on, the IP core can implement strict SFD checking, depending on register settings.
Configuration, Debug and Extension Options
Enable Native PHY Debug Master Endpoint (NPDME)	Boolean	True False	False	If turned on, the IP core turns on the following features in the Arria 10 PHY IP core that is included in the LL 40GbE IP core: Enable Native PHY Debug Master Endpoint (NPDME) Enable capability registers If turned off, the IP core is configured without these features. This parameter is available only in variations that target an Arria 10 device. For information about these Arria 10 features, refer to the Arria 10 Transceiver PHY User Guide.

Table 11. LL 40GbE Parameters: 40GBASE-KR4 TabDescribes the parameters for customizing a 40GBASE-KR4 Low Latency 40GbE IP core, on the 40GBASE-KR4 tab of the LL 40GbE parameter editor. The parameters on this tab are available only if the following conditions hold:

Your IP core targets an Arria 10 device. You set the target device family for your Intel^® Quartus^® Prime project or in the Intel^® Quartus^® Prime software before you acess the IP Catalog.

You turn off the Enable 1588 PTP parameter on the Main tab.
Parameter	Type	Range	Default Setting	Parameter Description
KR4 General Options
Enable KR4	Boolean	True False	False	If this parameter is turned on, the IP core is a 40GBASE-KR4 variation. If this parameter is turned off, the IP core is not a 40GBASE-KR4 variation, and the other parameters on this tab are not available.
Status clock rate	Frequency range	100–125 MHz	100 MHz	Sets the expected incoming `clk_status` frequency. The input clock frequency must match the frequency you specify for this parameter. The IP core is configured with this information: To ensure the IP core measures the link fail inhibit time accurately. Determines the value of the Link Fail Inhibit timer (IEEE 802.3 clause 73.10.2) correctly. If `clk_status` frequency is not 100 MHz, to adjust the PHY clock monitors to report accurate frequency information. This parameter determines the PHY Management clock (MGMT_CLK) frequency in MHz parameter of the underlying 10GBASE-KR PHY IP core. However, the default value of the Status clock rate parameter is not identical to the default value of the PHY IP core PHY Management clock (MGMT_CLK) frequency in MHz parameter.
Auto-Negotiation
Enable Auto-Negotiation	Boolean	True False	True	If this parameter is turned on, the IP core includes logic to implement auto-negotiation as defined in Clause 73 of IEEE Std 802.3ap–2007. If this parameter is turned off, the IP core does not include auto-negotiation logic and cannot perform auto-negotiation. Currently the IP core can only negotiate to KR4 mode.
Link fail inhibit time for 40Gb Ethernet	Integer (Unit: ms)	500–510 ms	504 ms	Specifies the time before link status is set to FAIL or OK. A link fails if the time duration specified by this parameter expires before link status is set to OK. For more information, refer to Clause 73 Auto-Negotiation for Backplane Ethernet in IEEE Standard 802.3ap–2007. The 40GBASE-KR4 IP core asserts the `rx_pcs_ready` signal to indicate link status is OK.
Auto-Negotiation Master	String	Lane 0 Lane 1 Lane 2 Lane 3	Lane 0	Selects the master channel for auto-negotiation.
Pause ability–C0	Boolean	True False	True	If this parameter is turned on, the IP core indicates on the Ethernet link that it supports symmetric pauses as defined in Annex 28B of Section 2 of IEEE Std 802.3–2008.
Pause ability–C1	Boolean	True False	True	If this parameter is turned on, the IP core indicates on the Ethernet link that it supports asymmetric pauses as defined in Annex 28B of Section 2 of IEEE Std 802.3–2008.
Link Training: PMA Parameters
VMAXRULE	Integer	0–31	30	Specifies the maximum V_OD. The default value, 60, represents 1200 mV.
VMINRULE	Integer	0–31	6	Specifies the minimum V_OD. The default value, 9, represents 165 mV.
VODMINRULE	Integer	0–31	14	Specifies the minimum V_OD for the first tap. The default value, 24, represents 440 mV.
VPOSTRULE	Integer	0–25	25	Specifies the maximum value that the internal algorithm for pre-emphasis will ever test in determining the optimum post-tap setting.
VPRERULE	Integer	0–16	16	Specifies the maximum value that the internal algorithm for pre-emphasis will ever test in determining the optimum pre-tap setting.
PREMAINVAL	Integer	0–31	30	Specifies the Preset V_OD value. This value is set by the Preset command of the link training protocol, defined in Clause 72.6.10.2.3.1 of IEEE Std 802.3ap–2007.
PREPOSTVAL	Integer	0–25	0	Specifies the preset Post-tap value.
PREPREVAL	Integer	0–16	0	Specifies the preset Pre-tap value.
INITMAINVAL	Integer	0–31	25	Specifies the initial V_OD value. This value is set by the Initialize command of the link training protocol, defined in Clause 72.6.10.2.3.2 of IEEE Std 802.3ap–2007.
INITPOSTVAL	Integer	0–25	13	Specifies the initial Post-tap value.
INITPREVAL	Integer	0–16	3	Specifies the initial Pre-tap value.
Link Training: General
Enable Link Training	Boolean	True False	True	If this parameter is turned on, the IP core includes the link training module, which configures the remote link partner TX PMD for the lowest Bit Error Rate (BER). LT is defined in Clause 72 of IEEE Std 802.3ap–2007.
Maximum bit error count	Integer	2ⁿ – 1 for n an integer in the range 4–10.	511	Specifies the maximum number of errors on a lane before the `Link Training Error` bit (40GBASE-KR4 register offset 0xD2, bit 4, 12, 20, or 28, depending on the lane) is set, indicating an unacceptable bit error rate. n is the width of the Bit Error Counter that is configured in the IP core. The value to which you set this parameter determines n, and thus the width of the Bit Error Counter. Because the default value of this parameter is 511, the default width of the Bit Error Counter is 10 bits. You can use this parameter to tune PMA settings. For example, if you see no difference in error rates between two different sets of PMA settings, you can increase the width of the bit error counter to determine if a larger counter enables you to distinguish between PMA settings.
Number of frames to send before sending actual data	Integer	127 255	127	Specifies the number of additional training frames the local link partner delivers to ensure that the link partner can correctly detect the local receiver state.
FEC Options
Include FEC sublayer	Boolean	True False	False	If this parameter is turned on, the IP core includes logic to implement FEC
Set FEC_Ability bit on power up or reset	Boolean	True False	True	If this parameter is turned on, the IP core sets the FEC ability bit (40GBASE-KR4 register offset 0xB0, bit 16: `KR FEC enable`) on power up and reset. This parameter is available if you turn on Include FEC sublayer.
Set FEC_Enable bit on power up or reset	Boolean	True False	True	If this parameter is turned on, the IP core sets the FEC enable bit (40GBASE-KR4 register offset 0xB0, bit 18: `KR FEC request`) on power up and reset. If you turn on this parameter but do not turn on Set FEC_ability bit on power up or reset, this parameter has no effect: the IP core cannot specify the value of 1 for FEC Requested without specifying the value of 1 for FEC Ability. This parameter is available if you turn on Include FEC sublayer.

Table 12. LL 40GbE PHY Parameter SettingsLists the PHY parameters that are configured automatically based on parameter values you select in the LL 40GbE parameter editor.
Parameter	Value
Lanes	4
Data rate per lane	10312.5 Mbps
Available PHY reference clock frequencies	322.265625 MHz 644.53125 MHz

2.5. Files Generated for Stratix V Variations

The Intel^® Quartus^® Prime Standard Edition software generates the following output for your Stratix V LL 40GbE IP core.

Figure 5. LL 40GbE IP Core Generated Files for Stratix V Variations

2.6. Files Generated for Arria 10 Variations

The Intel^® Quartus^® Prime software generates the following IP core output file structure when targeting Arria 10 devices.

For information about the file structure of the design example, refer to the LL 40GbE Design Example User Guide.

Figure 6. LL 40GbE IP Core Generated Files for Arria 10 Variations

Table 13. IP Core Generated Files
File Name	Description
<`your_ip`>.qsys ( Intel^® Quartus^® Prime Standard Edition only)	The Platform Designer (Standard) system or top-level IP variation file. <`your_ip`> is the name that you give your IP variation.
<`your_ip`>.ip ( Intel^® Quartus^® Prime Pro Edition only)
<`system`>.sopcinfo	Describes the connections and IP component parameterizations in your Platform Designer (Standard) system. You can parse its contents to get requirements when you develop software drivers for IP components. ( Intel^® Quartus^® Prime Standard Edition only) Downstream tools such as the Nios^® II tool chain use this file. The .sopcinfo file and the system.h file generated for the Nios^® II tool chain include address map information for each slave relative to each master that accesses the slave. Different masters may have a different address map to access a particular slave component.
<`your_ip`>.cmp	The VHDL Component Declaration (.cmp) file is a text file that contains local generic and port definitions that you can use in VHDL design files. This IP core does not support VHDL. However, the Intel^® Quartus^® Prime software generates this file.
<`your_ip`>.html	A report that contains connection information, a memory map showing the address of each slave with respect to each master to which it is connected, and parameter assignments.
<`your_ip`>_generation.rpt	IP or Platform Designer (Standard) generation log file. A summary of the messages during IP generation.
<`your_ip`>.debuginfo	Contains post-generation information. Used to pass System Console and Bus Analyzer Toolkit information about the Platform Designer (Standard) interconnect. The Bus Analysis Toolkit uses this file to identify debug components in the Platform Designer (Standard) interconnect. ( Intel^® Quartus^® Prime Standard Edition only)
<`your_ip`>.qgsimc	Lists simulation parameters to support incremental regeneration. ( Intel^® Quartus^® Prime Pro Edition only)
<`your_ip`>.qgsynthc	Lists synthesis parameters to support incremental regeneration. ( Intel^® Quartus^® Prime Pro Edition only)
<`your_ip`>.qip	Contains all the required information about the IP component to integrate and compile the IP component in the Intel^® Quartus^® Prime.
<`your_ip`>.csv	Contains information about the upgrade status of the IP component.
`<your_ip>`.bsf	A Block Symbol File (.bsf) representation of the IP variation for use in Intel^® Quartus^® Prime Block Diagram Files (.bdf).
<`your_ip`>.spd	Required input file for `ip-make-simscript` to generate simulation scripts for supported simulators. The .spd file contains a list of files generated for simulation, along with information about memories that you can initialize.
<`your_ip`>.ppf	The Pin Planner File (.ppf) stores the port and node assignments for IP components created for use with the Pin Planner.
<`your_ip`>_bb.v	You can use the Verilog black-box (_bb.v) file as an empty module declaration for use as a black box.
<`your_ip`>.sip	Contains information required for NativeLink simulation of IP components. You must add the .sip file to your Intel^® Quartus^® Prime project.
<`your_ip`>_inst.v or _inst.vhd	HDL example instantiation template. You can copy and paste the contents of this file into your HDL file to instantiate the IP variation. This IP core does not support VHDL. However, the Intel^® Quartus^® Prime software generates this file.
<`your_ip`>.regmap	If IP contains register information, .regmap file generates. The .regmap file describes the register map information of master and slave interfaces. This file complements the .sopcinfo file by providing more detailed register information about the system. This enables register display views and user customizable statistics in the System Console.
<`your_ip`>.svd	Allows hard processor system (HPS) System Debug tools to view the register maps of peripherals connected to HPS within a Platform Designer (Standard) system. During synthesis, the .svd files for slave interfaces visible to System Console masters are stored in the .sof file in the debug section. System Console reads this section, which Platform Designer (Standard) can query for register map information. For system slaves, Platform Designer (Standard) can access the registers by name.
<`your_ip`>.v or <`your_ip`>.vhd	HDL files that instantiate each submodule or child IP core for synthesis or simulation. This IP core does not support VHDL. However, the Intel^® Quartus^® Prime software generates this file.
mentor/	Contains a ModelSim* script msim_setup.tcl to set up and run a simulation.
aldec/	Contains a Riviera-PRO* script rivierapro_setup.tcl to setup and run a simulation.
synopsys/vcs/ synopsys/vcsmx/	Contains a shell script vcs_setup.sh to set up and run a VCS^® simulation. Contains a shell script vcsmx_setup.sh and synopsys_ sim.setup file to set up and run a VCS* MX simulation.
cadence/	Contains a shell script ncsim_setup.sh and other setup files to set up and run an NCSIM simulation.
submodules/	Contains HDL files for the IP core submodule.
<`child IP cores`>/	For each generated child IP core directory, Platform Designer (Standard) generates synth/ andsim/ sub-directories.

2.7. Integrating Your IP Core in Your Design

When you integrate your IP core instance in your design, you must pay attention to the following items:

2.7.1. Pin Assignments

When you integrate your LL 40GbE IP core instance in your design, you must make appropriate pin assignments. You can create a virtual pin to avoid making specific pin assignments for top-level signals until you are ready to map the design to hardware.

For the Arria 10 device family, you must configure a transceiver PLL that is external to the LL 40GbE IP core. The transceiver PLLs you configure are physically present in the device transceivers, but the LL 40GbE IP core does not configure and connect them. The required number of transceiver PLLs depends on the distribution of your Ethernet data pins in the different Arria 10 transceiver blocks.

2.7.2. External Transceiver Reconfiguration Controller Required in Stratix V Designs

LL 40GbE IP cores that target Stratix V devices require an external reconfiguration controller to compile and to function correctly in hardware. LL 40GbE IP cores that target Arria 10 devices include a reconfiguration controller block in the PHY component and do not require an external reconfiguration controller.

You can use the IP Catalog to generate an Transceiver Reconfiguration Controller.

When you configure the Transceiver Reconfiguration Controller, you must specify the number of reconfiguration interfaces. Stratix V LL 40GbE IP cores require 8 reconfiguration interfaces.

You can configure your reconfiguration controller with additional interfaces if your design connects with multiple transceiver IP cores. You can leave other options at the default settings or modify them for your preference.

You should connect the reconfig_to_xcvr, reconfig_from_xcvr, and reconfig_busy ports of the LL 40GbE IP core to the corresponding ports of the reconfiguration controller.

You must also connect the mgmt_clk_clk and mgmt_rst_reset ports of the Transceiver Reconfiguration Controller. The mgmt_clk_clk port must have a clock setting in the range of 100–125MHz; this setting can be shared with the LL 40GbE IP core clk_status port. The mgmt_rst_reset port must be deasserted before, or deasserted simultaneously with, the LL 40GbE IP core reset_async port.

Refer to the example project for RTL that connects the transceiver reconfiguration controller to the IP core.

Table 14. External Transceiver Reconfiguration Controller Ports for Connection to LL 40GbE IP Core
Signal Name	Direction	Description
`reconfig_to_xcvr[559:0]`	Input	The LL 40GbE IP core reconfiguration controller to transceiver port in Stratix V devices.
`reconfig_from_xcvr[367:0]`	Output	The LL 40GbE IP core reconfiguration controller from transceiver port in Stratix V devices.
`reconfig_busy`	Input	Indicates the reconfiguration controller is still in the process of reconfiguring the transceiver.

2.7.3. Transceiver PLL Required in Arria 10 Designs

LL 40GbE IP cores that target an Arria 10 device require an external TX transceiver PLL to compile and to function correctly in hardware.

Figure 7. PLL Configuration ExampleIn this example, the TX transceiver PLL is instantiated with an Arria 10 ATX PLL IP core. The TX transceiver PLL must always be instantiated outside the LL 40GbE IP core.

In this example, Use external TX MAC PLL is turned off. Therefore, the TX MAC PLL is in the IP core. If you turn on the Use external TX MAC PLL parameter you must also instantiate and connect a TX MAC PLL outside the LL 40GbE IP core.

You can use the IP Catalog to create a transceiver PLL.

Select Arria 10 Transceiver ATX PLL or Arria 10 Transceiver CMU PLL.
In the parameter editor, set the following parameter values:
- PLL output frequency to 5156.25 MHz . The transceiver performs dual edge clocking, using both the rising and falling edges of the input clock from the PLL. Therefore, this PLL output frequency setting supports a 10.3125 data rate through the transceiver.
- PLL reference clock frequency to the value you specified for the PHY reference frequency parameter.

When you generate a LL 40GbE IP core, the software also generates the HDL code for an ATX PLL, in the file <variation_name> /arria10_atx_pll.v. However, the HDL code for the LL 40GbE IP core does not instantiate the ATX PLL. If you choose to use the ATX PLL provided with the LL 40GbE IP core, you must instantiate and connect the instances of the ATX PLL with the LL 40GbE IP core in user logic.

Note: If your Arria 10 design includes multiple instances of the LL 40GbE IP core, do not use the ATX PLL HDL code provided with the IP core. Instead, generate new TX PLL IP cores to connect in your design.

The number of external PLLs you must generate or instantiate depends on the distribution of your Ethernet TX serial lines across physical transceiver channels and banks. You specify the clock network to which each PLL output connects by setting the clock network in the PLL parameter editor. The example project demonstrates one possible choice, which is compatible with the ATX PLL provided with the LL 40GbE IP core.

You must connect the tx_serial_clk input pin for each LL 40GbE IP core PHY link to the output port of the same name in the corresponding external PLL. You must connect the pll_locked input pin of the LL 40GbE IP core to the logical AND of the pll_locked output signals of the external PLLs for all of the PHY links.

User logic must provide the AND function and connections. Refer to the example compilation project or design example for working user logic that demonstrates one correct method to instantiate and connect an external PLL.

2.7.4. Handling Potential Jitter in Intel Arria 10 Devices

The RX path in the LL 40GbE core includes cascaded PLLs. Therefore, the IP core clocks might experience additional jitter in Intel^® Arria^® 10 devices.

Refer to the KDB Answer How do I compensate for the jitter of PLL cascading or non-dedicated clock path for Arria 10 PLL reference clock? for a workaround you should apply to the IP core, in your design.

2.7.5. External Time-of-Day Module for Variations with 1588 PTP Feature

LL 40GbE IP cores that include the 1588 PTP module require an external time-of-day (TOD) module to provide a continuous flow of current time-of-day information. The TOD module must update the time-of-day output value on every clock cycle, and must provide the TOD value in the V2 format (96 bits) or the 64-bit TOD format, or both.

The example project you can generate for your IP core PTP variation includes a TOD module, implemented as two distinct, simple TOD modules, one connected to the TX MAC and one connected to the RX MAC.

Table 15. TOD Module Required ConnectionsRequired connections for TOD module, listed using signal names for TOD modules that provide both a 96-bit TOD and a 64-bit TOD. If you create your own TOD module it must have the output signals required by the LL 40GbE IP core. However, its signal names could be different than the TOD module signal names in the table. The signals that that the IP core includes depend on the Enable 96b Time of Day Format and Enable 64b Time of Day Format parameters. For example, an RX TOD module might require only a 96-bit TOD out signal.
TOD Module Signal	LL 40GbE IP Core Signal
`rst_txmac` (input)	Drive this signal from the same source as the `reset_async` input signal to the LL 40GbE IP core.
`rst_rxmac` (input)	Drive this signal from the same source as the `reset_async` input signal to the LL 40GbE IP core.
`tod_txmclk_96b[95:0]` (output)	`tx_time_of_day_96b_data[95:0]` (input)
`tod_txmclk_64b[63:0]` (output)	`tx_time_of_day_64b_data[63:0]` (input)
`tod_rxmclk_96b[95:0]` (output)	`rx_time_of_day_96b_data[95:0]` (input)
`tod_rxmclk_64b[63:0]` (output)	`rx_time_of_day_64b_data[63:0]` (input)
`clk_txmac` (input)	`clk_txmac` (output)
`clk_rxmac` (input)	`clk_rxmac` (output)

2.7.6. Clock Requirements for 40GBASE-KR4 Variations

In 40GBASE-KR4 IP core designs, you must drive the clocks for the two IP core register interfaces (reconfig_clk and clk_status) from the same clock source.

2.7.7. External TX MAC PLL

If you turn on Use external TX MAC PLL in the LL 40GbE parameter editor, you must connect the clk_txmac_in input port to a clock source, usually a PLL on the device.

The clk_txmac_in signal drives the clk_txmac clock in the IP core TX MAC and PHY. If you turn off this parameter, the clk_txmac_in input clock signal is not available.

The required TX MAC clock frequency is 312.5 MHz . User logic must drive clk_txmac_in from a PLL whose input is the PHY reference clock, clk_ref.

2.7.8. Placement Settings for the LL 40GbE Core

The Quartus Prime software provides the options to specify design partitions and Logic Lock (Standard) or Logic Lock regions for incremental compilation, to control placement on the device. To achieve timing closure for your design, you might need to provide floorplan guidelines using one or both of these features.

The appropriate floorplan is always design-specific, and depends on your design.

2.8. IP Core Testbenches

Intel provides a testbench, a hardware design example, and a compilation-only design example with most variations of the LL 40GbE IP core. The testbench is available for simulation of your IP core, and the hardware design example can be run on hardware. You can run the testbench to observe the IP core behavior on the various interfaces in simulation.

Intel offers testbenches for all Avalon-ST client interface variations that generate their own TX MAC clock(Use external TX MAC PLL is turned off).

Currently, the IP core can generate a testbench and example project for variations that use an external TX MAC PLL, but these testbenches and example projects do not function correctly. Non-functional testbenches and example projects provide an example of the connections you must create in your design to ensure the LL 40GbE IP core functions correctly. However, you cannot simulate them nor run them in hardware.

To generate the testbench, in the LL 40GbE parameter editor, you must first set the parameter values for the IP core variation you intend to generate in your end product. If you do not set the parameter values for your DUT to match the parameter values in your end product, the testbench you generate does not exercise the IP core variation you intend. If your IP core variation does not meet the criteria for a testbench, the generation process does not create a testbench (with the exception of the non-functional testbench generated if an IP core requires an external TX MAC clock signal).

You can simulate the testbench that you generate with your IP core variation. The testbench illustrates packet traffic, in addition to providing information regarding the transceiver PHY. The 40GBASE-KR4 testbench exercises auto-negotiation and link training, in addition to generating and checking packet traffic.

The testbench demonstrates a basic test of the IP core. It is not intended to be a substitute for a full verification environment.

2.8.1. Testbench Behavior

The non-40GBASE-KR4 testbenches send traffic through the IP core in transmit-to-receive loopback mode, exercising the transmit side and receive side of the IP core in the same data flow. These testbenches send traffic to allow the Ethernet lanes to lock, and then send packets to the transmit client data interface and check the data as it returns through the receive client data interface.

The 40GBASE-KR4 testbench sends traffic through the two IP cores in each direction, exercising the receive and transmit sides of both IP cores. This testbench exercises auto-negotiation and link training, and then sends and checks packets in data mode.

Figure 8. LL 40GbE non-40GBASE-KR4 IP Core Testbench The top-level testbench file consists of a simple packet generator and checker and one IP core in a loopback configuration.

Figure 9. 40GBASE-KR4 LL 40GbE IP Core TestbenchTo support the simulation of auto-negotiation, the testbench for 40GBASE-KR4 variations uses two instances of the IP core instead of configuring the IP core in loopback mode. For each IP core there is a packet generator to send traffic on the TX side of the IP core and a packet checker to check the packets it receives from the other IP core. The two IP cores communicate with each other through their Ethernet link, in which the testbench injects random skew. The 40GBASE-KR4 testbench connects each IP core to a transceiver TX PLL, and exercises auto-negotiation, link training, and data mode.

Figure 10. Typical LL 40GbE Traffic on the Avalon-ST InterfaceShows typical traffic from the simulation testbench created using the run_vsim.do script in ModelSim. In Stratix V variations the script is found in <instance_name> _example_design/alt_eth_ultra/example_testbench/run_vsim.do and in Arria 10 variations the script is found in <example_design_directory> /example_testbench/run_vsim.do.

Note: Client logic must maintain the l4_tx_valid signal asserted while asserting SOP, through the assertion of EOP. Client logic should not pull this signal low during a packet transmission.

The markers in the figure show the following sequence of events:

At marker 1, the application asserts l4_tx_startofpacket, indicating the beginning of a TX packet.
At marker 2, the application asserts l4_tx_endofpacket, indicating the end of the TX packet. The value on l4_tx_empty[4:0] indicates that the 2 least significant bytes of the last data cycle are empty.
At marker 3, the IP core asserts l4_rx_startofpacket, indicating the beginning of an RX packet. A second transfer has already started on the TX bus.
At marker 4, the 40GbE IP core deasserts l4_rx_valid, indicating that the IP core does not have new valid data to send to the client on l4_rx_data[255:0]. l4_rx_data[255:0] remains unchanged for a second cycle, but because the l4_rx_valid signal is deasserted, the client should ignore the value on the RX signals.
A marker 5, the 40GbE IP core asserts l4_rx_valid, indicating that it has valid data to send to the client on l4_rx_data[255:0].
At marker 6, the 40GbE IP core deasserts l4_rx_valid, indicating that it does not have new valid data to send to the client on l4_rx_data[255:0]. l4_rx_data[255:0] remains unchanged for a second cycle.
At marker 7, the 40GbE IP core asserts l4_rx_valid, indicating that it has valid data to send to the client on l4_rx_data[255:0].
At marker 8, the 40GbE IP core deasserts l4_rx_valid, indicating that the 40GbE IP core does not have new valid data to send to the client on l4_rx_data[255:0]. l4_rx_data[255:0] remains unchanged for a second cycle.
At marker 9, the IP core asserts l4_rx_endofpacket, indicating the end of the RX packet. l4_rx_empty[4:0] has a value of 0x1D, indicating that 29 least significant bytes of the last cycle of the RX packet empty.

Note: The ready latency on the Avalon-ST TX client interface is 0.

2.8.2. Simulating the LL 40GbE IP Core With the Testbenches

You can simulate the LL 40GbE IP core using the Intel-supported versions of the Mentor Graphics ModelSim^® SE, Cadence NCSim, and Synopsys VCS simulators for the current version of the Quartus Prime software. The ModelSim^® - Intel FPGA Edition simulator does not have the capacity to simulate this IP core.

The example testbenches simulate packet traffic at the digital level. The testbenches do not require special SystemVerilog class libraries.

The example testbenches contain the test files and run scripts for the ModelSim, Cadence, and Synopsys simulators. The run scripts use the file lists in the wrapper files. When you launch a simulation from the original directory, the relative filenames in the wrapper files allow the run script to locate the files correctly. When you generate the testbench for a LL 40GbE IP core that targets an Arria 10 device, the software generates a copy of the IP core variation with a specific relative path from the testbench scripts.

Table 16. LL 40GbE IP Core Testbench File DescriptionsLists the key files that implement the example testbenches.
File Names	Description
Testbench and Simulation Files
basic_avl_tb_top.v	Top-level testbench file for non-40GBASE-KR4 variations. The testbench instantiates the DUT and runs Verilog HDL tasks to generate and accept packets.
alt_e40_avalon_kr4_tb.sv	Top-level testbench file for 40GBASE-KR4 variations.
alt_e40_avalon_tb_packet_gen.v, alt_e40_avalon_tb_packet_gen_sanity_check.v, alt_e40_stat_cntr_1port.v	Packet generator and checkers for 40GBASE-KR4 variations.
Testbench Scripts
run_vsim.do	The ModelSim script to run the testbench. Note: The ModelSim^® - Intel FPGA Edition simulator does not have the capacity to simulate this IP core. You must use another supported ModelSim simulator.
run_vcs.sh	The Synopsys VCS script to run the testbench.
run_ncsim.sh	The Cadence NCSim script to run the testbench.

2.8.2.1. Generating the LL 40GbE Testbench

A single procedure generates the testbench and example project (for Stratix V variations) or the testbench, compilation-only design example, and hardware design example (for Arria 10 variations). The procedure varies depending on your target device. To generate these demonstration aids:

Follow the steps in Specifying the IP Core Parameters and Options to parameterize your IP core.
If your IP core variation targets a Stratix V device, go to step 4.
If your IP core variation targets an Arria 10 device, in the LL 40GbE parameter editor:
- On the Example Design tab, select Simulation, Synthesis, or both to specify whether you want to generate the simulation-only testbench, the compilation-only and hardware design examples, or all three options.
- Click the Generate Example Design button to generate these options for the IP core variation you intend to generate.
Tip: You are prompted to locate the new testbench and example project in the directory <working directory>/alt_eth_ultra_40_0_example_design . You can accept the default path or modify the path to the new testbench and example project.
Generate the IP core by clicking Generate HDL for Arria 10 variations or Generate for Stratix V variations.
Note: If your IP core variation targets a Stratix V device, when prompted at the start of generation, you must turn on Generate example design. Turning on Generate example design is the only process that generates a functional testbench and a functional example project for Stratix V variations.

When the IP core is generated in <working directory>, the testbench and example projects are generated in different locations depending on the device family your IP core variation targets.
- For Stratix V variations, the testbench and example project are generated in <working directory>/<IP core variation>_example_design/alt_eth_ultra.
- For Arria 10 variations, the testench and the compilation-only and hardware design examples are generated in the directory you specify in Step 3. If you do not modify the location text at the prompt, they are generated in <working directory>/alt_eth_ultra_40_0_example_design .

The directory with the testbench and design example has four subdirectories for Arria 10 variations and three subdirectories for Stratix V variations:

example_testbench
compilation_test_design
hardware_test_design
ex_40g , for Arria 10 variations only

The ex_40g directory contains a copy of the IP core variation. The testbench and design examples (compilation-only and hardware design example) for your Arria 10 IP core variation connect to the copy in this directory rather than to the copy you generate in <working directory>.

2.8.2.2. Optimizing the IP Core Simulation With the Testbenches

In the testbench file for non-40GBASE-KR4 variations, you can set the FASTSIM parameter and force values in the RO_SELS, BPOS, and WPOS parameters to enable simulation optimization. The testbench also specifies another IP core simulation optimization setting that you might need to modify for simulation in your own environment: AM_CNT_BITS.

To derive the values to which to force the RO_SELS, BPOS, and WPOS parameters, you must run your first simulation with some additional testbench code to display the simulation-derived values. For subsequent simulation runs with the same hardware design and simulator, you can force the values to these simulation-derived values to avoid the lengthy simulation required to achieve lane alignment. The process is particularly slow for this IP core because the IP core includes a soft processor that drives the lane alignment process. Forcing the parameters to the correct values for your design and simulator bypasses this process, increasing simulation efficiency.

The testbench file generated with the LL 40GbE IP core includes an initial block that displays the required force values. You can view the appropriate initial block for your IP core variation in the top-level testbench file you generate with your example design.

When you run simulation, this initial block prints values for the three parameters after lane alignment. Copy the values from standard output or from your log file and add the following lines to the testbench file, overwriting other forced values for these parameters if necessary:

defparam dut.top_inst.FASTSIM = 1;
defparam dut.<variation_name>_inst.FORCE_BPOS = <required BPOS value>;
defparam dut.<variation_name>_inst.FORC_WPOS  = <required WPOS value>;
defparam dut.<variation_name>_inst.FORCE_RO_SELS = <required RO_SELS value>;

Note: Whether you use the Intel-provided testbench or your own custom testbench, you must update the testbench file with these lines and the derived values. The testbench file generated with the LL 40GbE IP core does not include the correct values, which depend on your IP core variation and simulation tool.

The AM_CNT_BITS parameter specifies the interval between expected alignment markers. The default value of this parameter is 14; this value specifies that alignment markers are inserted every 2¹⁴ blocks, in compliance with the Ethernet specification. However, the testbench sets this parameter to the value of 6, to speed up simulation. In your own simulation environment, you must set this parameter to match the interval between incoming alignment markers to the IP core.

2.8.2.3. Optimization in the 40GBASE-KR4 Testbench

In the 40GBASE-KR4 testbench, some register values are set to produce a shorter runtime. For example, timeout counters and the number of steps used in link training are set to smaller values than would be prudent in hardware. To override this behavior and use the normal settings in simulation, add the following line to your IP core variation top-level file or to the testbench top-level file, alt_e40_avalon_kr4_tb.sv:

`define ALTERA_RESERVED_XCVR_FULL_KR_TIMERS

2.8.2.4. Simulating with the Modelsim Simulator

To run the simulation in the supported versions of the ModelSim simulation tool, follow these steps:

Change directory to the <example_design_install_dir>/example_testbench directory.
In the command line, type: vsim -c -do run_vsim.do

The example testbench will run and pass.

The ModelSim^® - Intel FPGA Edition simulator does not have the capacity to simulate this IP core.

2.8.2.5. Simulating with the NCSim Simulator

To run the simulation in the supported versions of the NCSim simulation tool, follow these steps:

Change directory to the <example_design_install_dir>/example_testbench directory.
In the command line, type: sh run_ncsim.sh
The example testbench will run and pass.

2.8.2.6. Simulating with the VCS Simulator

To run the simulation in the supported versions of the VCS simulation tool, follow these steps:

Change directory to the <example_design_install_dir>/example_testbench directory.
In the command line, type: sh run_vcs.sh

The example testbench will run and pass.

2.8.2.7. Testbench Output Example

This section shows successful simulation using the LL 40GbE IP core testbench (<variation_name> _example_design/alt_eth_ultra/example_testbench/basic_avl_tb_top.v for Stratix V variations, or <example_design_directory> /example_testbench/basic_avl_tb_top.v for Arria 10 variations). The testbench connects the Ethernet TX lanes to the Ethernet RX lanes, so that the IP core is in an external loopback configuration. In simulation, the testbench resets the IP core and waits for lane alignment and deskew to complete successfully. The packet generator sends ten packets on the Ethernet TX lanes and the packet checker checks the packets when the IP core receives them on the Ethernet RX lanes.

The successful testbench run displays the following output:

# *****************************************
# ** Starting TX traffic...
# **
# **
# ** Sending Packet           1...
# ** Sending Packet           2...
# ** Sending Packet           3...
# ** Sending Packet           4...
# ** Sending Packet           5...
# ** Sending Packet           6...
# ** Sending Packet           7...
# ** Sending Packet           8...
# ** Sending Packet           9...
# ** Sending Packet          10...
# ** Received Packet          1...
# ** Received Packet          2...
# ** Received Packet          3...
# ** Received Packet          4...
# ** Received Packet          5...
# ** Received Packet          6...
# ** Received Packet          7...
# ** Received Packet          8...
# ** Received Packet          9...
# ** Received Packet         10...
# **
# ** Testbench complete.
# **
# *****************************************

2.9. Compiling the Full Design and Programming the FPGA

You can use the Start Compilation command on the Processing menu in the Intel^® Quartus^® Prime software to compile your design. After successfully compiling your design, program the targeted Intel device with the Programmer and verify the design in hardware.

Note: The LL 40GbE IP core design example synthesis directories include Synopsys Constraint (.sdc) files that you can copy and modify for your own design.

Note: For additional .sdc file requirements for Intel^® Arria^® 10 designs, please refer to the KDB Answer at https://www.altera.com/support/support-resources/knowledge-base/tools/2017/fb470823.html.

2.10. Initializing the IP Core

The testbench initializes the IP core. However, when you simulate or run your own design in hardware, you must implement the initialization steps yourself.

To initialize the LL 40GbE IP core in your own design, follow these steps:

Drive the clock ports.
Reset the IP core.

3. Functional Description

This chapter provides a detailed description of the LL 40GbE IP core. The chapter begins with a high-level overview of typical Ethernet systems and then provides detailed descriptions of the MAC, transmit (TX) and receive (RX) datapaths, signals, register descriptions, and an Ethernet glossary. This chapter includes the following sections:

3.1. High Level System Overview

Figure 11. LL 40GbE IP CoreMain blocks, internal connections, and external block requirements.

3.2. LL 40GbE IP Core Functional Description

The LL 40GbE IP core implements the 40 GbE Ethernet MAC in accordance with the IEEE 802.3ba 2010 High Speed Ethernet Standard. This IP core handles the frame encapsulation and flow of data between a client logic and Ethernet network via a 40 GbE Ethernet PCS and PMA (PHY).

In the transmit direction, the MAC accepts client frames, and inserts inter-packet gap (IPG), preamble, start of frame delimiter (SFD), padding, and CRC bits before passing them to the PHY. The PHY encodes the MAC frame as required for reliable transmission over the media to the remote end.

In the receive direction, the PHY passes frames to the MAC. The MAC accepts frames from the PHY, performs checks, updates statistics counters, strips out the CRC, preamble, and SFD, and passes the rest of the frame to the client. In RX preamble pass-through mode, the MAC passes on the preamble and SFD to the client instead of stripping them out. In RX CRC pass-through mode (bit 1 of the CRC_CONFIG register has the value of 1), the MAC passes on the CRC bytes to the client and asserts the EOP signal in the same clock cycle with the final CRC byte.

The LL 40GbE IP core includes the following interfaces:

Datapath client-interface–The following options are available:
- With adapters—Avalon-ST, 256 bits
- Custom streaming, 128 bits
Management interface—Avalon-MM host slave interface for MAC management. This interface has a data width of 32 bits and an address width of 16 bits.
Datapath Ethernet interface—XLAUI interface: Four 10.3125 Gbps serial links
In Arria 10 variations, an Arria 10 dynamic reconfiguration interface—an Avalon-MM interface to read and write the Arria 10 Native PHY IP core registers. This interface supports dynamic reconfiguration of the transceiver. LL 40GbE IP cores that target an Arria 10 device use the Arria 10 Native PHY IP core to configure the Ethernet link serial transceivers on the device. This interface has a data width of 32 bits. This interface has an address width of 12 bits.

3.2.1. LL 40GbE IP Core TX Datapath

The TX MAC module receives the client payload data with the destination and source addresses and then adds, appends, or updates various header fields in accordance with the configuration specified. The MAC does not modify the destination address, the source address, or the payload received from the client. However, the TX MAC module adds a preamble (if the IP core is not configured to receive the preamble from user logic), pads the payload of frames greater than eight bytes to satisfy the minimum Ethernet frame payload of 46 bytes, and if you set Enable TX CRC insertion or turn on flow control, calculates the CRC over the entire MAC frame. (If padding is added, it is also included in the CRC calculation. If you turn off Enable TX CRC insertion, the client must provide the CRC bytes and must provide frames that have a minimum size of 64 bytes and therefore do not require padding). If you set Average interpacket gap to 8 or 12, the TX MAC module inserts IDLE bytes to maintain an average IPG. In addition, the TX MAC inserts an error in the Ethernet frame if the client requests to insert an error.

The LL 40GbE IP core does not process incoming frames of less than nine bytes correctly. You must ensure such frames do not reach the TX client interface.

Figure 12. Typical Client Frame at the Transmit InterfaceIllustrates the changes that the TX MAC makes to the client frame. This figure uses the following notational conventions:

<p> = payload size, which is arbitrarily large.
<s> = padding bytes = 0–46 bytes.
<g> = number of IPG bytes

The following sections describe the functions that the TX module performs:

3.2.1.1. Preamble, Start, and SFD Insertion

In the TX datapath the MAC appends an eight-byte preamble that begins with a Start byte (0xFB) to the client frame. If you turn on Enable link fault generation, this MAC module also incorporates the functions of the reconciliation sublayer.

The source of the preamble depends on whether you turn on the preamble pass-through feature by turning on Enable preamble passthrough in the LL 40GbE parameter editor.

If the preamble pass-through feature is turned on, the client provides the eight-byte preamble (including Start byte) on the data bus. The client is responsible for providing the correct Start byte.

3.2.1.2. Address Insertion

The client provides the destination MAC address and the source address of the local MAC.

3.2.1.3. Length/Type Field Processing

This two-byte header represents either the length of the payload or the type of MAC frame. When the value of this field is equal to or greater than 1536 (0x600) it indicates a type field. Otherwise, this field provides the length of the payload data that ranges from 0–1500 bytes. The TX MAC does not modify this field before forwarding it to the network.

3.2.1.4. Frame Padding

When the length of client frame is less than 64 bytes (meaning the payload is less than 46 bytes) and greater than eight bytes, the TX MAC module inserts pad bytes (0x00) after the payload to create a frame length equal to the minimum size of 64 bytes.

CAUTION:

The LL 40GbE IP core does not process incoming (egress) frames of less than nine bytes correctly. You must ensure such frames do not reach the TX client interface.

3.2.1.5. Frame Check Sequence (CRC-32) Insertion

The TX MAC computes and inserts a CRC32 checksum in the transmitted MAC frame. The frame check sequence (FCS) field contains a 32-bit CRC value. The MAC computes the CRC32 over the frame bytes that include the source address, destination address, length, data, and pad (if applicable). The CRC checksum computation excludes the preamble, SFD, and FCS. The encoding is defined by the following generating polynomial:

FCS(X) = X32 +X26 +X23 +X22 +X16 +X12 +X11 +X10 +X8 +X7 +X5 +X4 +X2 +X1 +1

CRC bits are transmitted with MSB (X32) first.

If you configure your LL 40GbE IP core with no flow control, you can configure your IP core TX MAC to implement TX CRC insertion or not, by turning Enable TX CRC insertion on or off in the LL 40GbE parameter editor. By default, the CRC insertion feature is enabled. In variations with flow control, CRC insertion is enabled.

3.2.1.6. Inter-Packet Gap Generation and Insertion

If you set Average interpacket gap to 12 in the LL 40GbE parameter editor, the TX MAC maintains the minimum inter-packet gap (IPG) between transmitted frames required by the IEEE 802.3 Ethernet standard. The standard requires an average minimum IPG of 96 bit times (or 12 byte times). The deficit idle counter maintains the average IPG of 12 bytes.

If you set Average interpacket gap to 8, the TX MAC maintains a minimum average IPG of 8 bytes. This option is provided as an intermediate option to allow you to enforce an IPG that does not conform to the Ethernet standard, but which increases the throughput of your IP core.

If you set Average interpacket gap to Disable deficit idle counter, the IP core transmits Ethernet packets as soon as the data is available, without maintaining the 12-byte IPG. In this case the IP core maintains only a minimum 1-byte IPG. If you select this parameter value, you optimize the IP core throughput.

3.2.1.7. Error Insertion Test and Debug Feature

The client can specify the insertion of a TX error in a specific packet. If the client specifies the insertion of a TX error, the LL 40GbE IP core inserts an error in the frame it transmits on the Ethernet link. The error appears as a 66-bit error block that consists of eight /E/ characters (EBLOCK_T) in the Ethernet frame.

To direct the IP core to insert a TX error in a packet, the client should assert the TX error insertion signal as follows, depending on the TX client interface:

On the Avalon-ST TX client interface, assert the l4_tx_error signal in the EOP cycle of the packet.
On the custom streaming TX client interface, assert bit N of the tx_error[1:0] signal in the same cycle in which bit N of din_eop[1:0] is asserted.

The IP core overwrites Ethernet frame data with an EBLOCK_T error block when it transmits the Ethernet frame that corresponds to the packet EOP.

This feature supports test and debug of your IP core. In loopback mode, when the IP core receives a deliberately errored packet on the Ethernet link, the IP core recognizes it as a malformed packet.

3.2.2. LL 40GbE IP Core TX Data Bus Interfaces

This section describes the TX data bus at the user interface and includes the following topics:

3.2.2.1. LL 40GbE IP Core User Interface Data Bus

The user interface width depends on your IP core variation. The LL 40GbE IP core provides two different client interfaces: the Avalon-ST interface and a custom interface.

Custom streaming interface (no adapters): Data bus width is 128 bits.
Avalon-ST interface: Data bus width is 256 bits.

Both interfaces operate at 312.5 MHz.

3.2.2.2. LL 40GbE IP Core TX Data Bus with Adapters (Avalon-ST Interface)

The LL 40GbE IP core TX datapath with adapters employs the Avalon-ST protocol. The Avalon-ST protocol is a synchronous point-to-point, unidirectional interface that connects the producer of a data stream (source) to a consumer of data (sink). The key properties of this interface include:

Start of packet (SOP) and end of packet (EOP) signals delimit frame transfers.
The SOP must always be in the MSB, simplifying the interpretation and processing of incoming data.
A valid signal qualifies signals from source to sink.
The sink applies backpressure to the source by using the ready signal. The source typically responds to the deassertion of the ready signal from the sink by driving the same data until the sink can accept it. The readyLatency defines the relationship between assertion and deassertion of the ready signal, and cycles which are considered to be ready for data transfer.The readyLatency on the TX client interface is zero cycles.

The client acts as a source and the TX MAC acts as a sink in the transmit direction.

Figure 13. TX Client to MAC Interface with Adapters (Avalon-ST)

Table 17. Signals of the Avalon-ST TX Client InterfaceAll interface signals are clocked by the `clk_txmac` clock.
Signal Name	Direction	Description
`l4_tx_data[255:0]`	Input	TX data. If the preamble pass-through feature is enabled, data begins with the preamble. The LL 40GbE IP core does not process incoming frames of less than nine bytes correctly. You must ensure such frames do not reach the TX client interface. You must send each TX data packet without intermediate IDLE cycles. Therefore, you must ensure your application can provide the data for a single packet in consecutive clock cycles. If data might not be available otherwise, you must buffer the data in your design and wait to assert `l4_tx_startofpacket` when you are assured the packet data to send on `l4_tx_data[255:0]` is available or will be available on time.
`l4_tx_empty[4:0]`	Input	Indicates the number of empty bytes on `l4_tx_data[255:0]` when `l4_tx_endofpacket` is asserted.
`l4_tx_startofpacket`	Input	When asserted, indicates the start of a packet. The packet starts on the MSB.
`l4_tx_endofpacket`	Input	When asserted, indicates the end of packet.
`l4_tx_ready`	Output	When asserted, the MAC is ready to receive data. The `l4_tx_ready` signal acts as an acknowledge. The source drives `l4_tx_valid` and `l4_tx_data[255:0]` , then waits for the sink to assert `l4_tx_ready` . The `readyLatency` is zero cycles, so that the IP core accepts valid data in the same cycle in which it asserts `l4_tx_ready` . The `l4_tx_ready` signal indicates the MAC is ready to receive data in normal operational model. However, the `l4_tx_ready` signal might not be an adequate indication following reset. To avoid sending packets before the Ethernet link is able to transmit them reliably, you should ensure that the application does not send packets on the TX client interface until after the `tx_lanes_stable` signal is asserted.
`l4_tx_valid`	Input	When asserted `l4_tx_data` is valid. This signal must be continuously asserted between the assertions of `l4_tx_startofpacket` and `l4_tx_endofpacket` for the same packet.
`l4_tx_error`	Input	When asserted in an EOP cycle (while `l4_tx_endofpacket` is asserted), directs the IP core to insert an error in the packet before sending it on the Ethernet link. This signal is a test and debug feature. In loopback mode, the IP core recognizes the packet upon return as a malformed packet.

Figure 14. Traffic on the TX and RX Avalon-ST Client Interface for Low Latency 40GbE IP CoreShows typical traffic for the TX and RX Avalon-ST interface Low Latency 40GbE IP core.

3.2.2.3. LL 40GbE IP Core TX Data Bus Without Adapters (Custom Streaming Interface)

Figure 15. TX Client to MAC Interface Without Adapters

Table 18. Signals of the Custom Streaming TX Client InterfaceAll interface signals are clocked by the `clk_txmac` clock.
Signal Name	Direction	Description
`din[127:0]`	Input	Data bytes to send in big-endian mode. Most significant 64-bit word is in the higher-order bits: bits[127:64] The LL 40GbE IP core does not process incoming frames of less than nine bytes correctly. You must ensure such frames do not reach the TX client interface.
`din_sop[1:0]`	Input	Start of packet (SOP) location in the TX data bus. Only the most significant byte of each 64‑bit word may be a start of packet. Bits 63 and 127 are the allowed locations. Bit 0 of `din_sop` corresponds to the data word in `din[63:0]`.
`din_eop[1:0]`	Input	End of packet location in the TX data bus. Indicates the 64-bit word that holds the end-of-packet byte. Any byte may be the last byte in a packet. Bit 0 of `din_eop` corresponds to the data word in `din[63:0]`.
`din_eop_empty[5:0]`	Input	Indicates the number of empty (invalid) bytes in the end-of-packet 8-byte word indicated by `din_eop`. If `din_eop[z]` has the value of 0, then the value of `din_eop_empty[(z+2):z]` does not matter. However, if `din_eop[z]` has the value of 1, then you must set the value of `din_eop_empty[(z+2):z]` to the number of empty (invalid) bytes in the end-of-packet word `z`. For example, if you have a LL 40GbE IP core and want to indicate that in the current `clk_txmac` clock cycle, byte 6 in word 1 of `din` is an end-of-packet byte, and no other words hold an end-of-packet byte in the current clock cycle, you must set the value of `din_eop` to 2'b10 and the value of `din_eop_empty` to 6'b110_000.
`din_idle[1:0]`	Input	Indicates the words in `din` that hold Idle bytes or control information rather than Ethernet data. One-hot encoded.
`din_req`	Output	Indicates that input data was accepted by the IP core.
`tx_error[1:0]`	Input	When asserted in an EOP cycle (while `din_eop` is non-zero), directs the IP core to insert an error in the corresponding packet before sending it on the Ethernet link. This signal is a test and debug feature. In loopback mode, the IP core recognizes the packet upon return as a malformed packet.
`clk_txmac`	Output	TX MAC clock. The clock frequency should be 312.5 MHz . The `clk_txmac` clock and the `clk_rxmac` clock (which clocks the RX datapath) are assumed to have the same frequency.

The IP core reads the bytes in big endian order. A packet may start in the most significant byte of any word. A packet may end on any byte.

3.2.2.4. Bus Quantization Effects With Adapters

The TX custom streaming interface allows a packet to start at any of two positions to maximize utilization of the link bandwidth. The TX Avalon-ST interface only allows start of packet (SOP) to be placed at the most significant position. If the SOP were restricted to the most significant position in the client logic data bus in the custom streaming interface, bus bandwidth would be reduced.

Figure 16. Reduced Bandwidth With Left-Aligned SOP Requirement Illustrates the reduction of bandwidth that would be caused by left-aligning the SOP for the LL 40GbE IP core.

The example shows a nine-word packet, which is the worst case for bandwidth utilization. Assuming another packet is waiting for transmission, the effective ingress bandwidth is reduced by 10%. Running the MAC portion of the logic slightly faster than is required can mitigate this loss of bandwidth. Additional increases in the MAC frequency can provide further mitigation, although increases in frequency make timing closure more difficult. The wider data bus for the Avalon-ST interface also helps to compensate for the Avalon-ST left-aligned SOP requirement.

3.2.2.5. User Interface to Ethernet Transmission

The IP core reverses the bit stream for transmission per Ethernet requirements. The transmitter handles the insertion of the inter-packet gap, frame delimiters, and padding with zeros as necessary. The transmitter also handles FCS computation and insertion.

The Ethernet MAC and PHY transmit complete packets. After transmission begins, it must complete with no IDLE insertions. Between the end of one packet and the beginning of the next packet, the data input is not considered and the transmitter sends IDLE characters. An unbounded number of IDLE characters can be sent between packets.

3.2.2.5.1. Order of Transmission

The IP core transmits bytes on the Ethernet link starting with the preamble and ending with the FCS in accordance with the IEEE 802.3 standard. Transmit frames the IP core receives on the client interface are big-endian. Frames the MAC sends to the PHY on the XGMII/CGMII between the MAC and the PHY are little-endian; the MAC TX transmits frames on this interface beginning with the least significant byte.

Figure 17. Byte Order on the Client Interface Lanes Without Preamble Pass-ThroughDescribes the byte order on the Avalon-ST interface when the preamble pass-through feature is turned off. Destination Address[40] is the broadcast/multicast bit (a type bit), and Destination Address[41] is a locally administered address bit.

For example, the destination MAC address includes the following six octets AC-DE-48-00-00-80. The first octet transmitted (octet 0 of the MAC address described in the 802.3 standard) is AC and the last octet transmitted (octet 7 of the MAC address) is 80. The first bit transmitted is the low-order bit of AC, a zero. The last bit transmitted is the high order bit of 80, a one.

The preceding table and the following figure show that in this example, 0xAC is driven on DA5 (DA[47:40]) and 0x80 is driven on DA0 (DA[7:0]).

Figure 18. Octet Transmission on the Avalon-ST Signals Without Preamble Pass-Through Illustrates how the octets of the client frame are transferred over the TX datapath when preamble pass-through is turned off.

Figure 19. Byte Order on the Avalon-ST Interface Lanes With Preamble Pass-ThroughDescribes the byte order on the Avalon-ST interface when the preamble pass-through feature is turned on.

Destination Address[40] is the broadcast/multicast bit (a type bit), and Destination Address[41] is a locally administered address bit.

Figure 20. Octet Transmission on the Avalon-ST Signals With Preamble Pass-ThroughIllustrates how the octets of the client frame are transferred over the TX datapath when preamble pass-through is turned on. The eight preamble bytes precede the destination address bytes. The preamble bytes are reversed: the application must drive the Start byte on l8_tx_data[199:192] and the SFD byte on l8_tx_data[255:248].

The destination address and source address bytes follow the preamble pass-through in the same order as in the case without preamble pass-through.

3.2.3. LL 40GbE IP Core RX Datapath

The LL 40GbE RX MAC receives Ethernet frames from the PHY and forwards the payload with relevant header bytes to the client after performing some MAC functions on header bytes.

Figure 21. Flow of Frame Through the MAC RX Without Preamble Pass-Through Illustrates the typical flow of frame through the MAC RX when the preamble pass-through feature is turned off. In this figure, <p> is payload size, and <s> is the number of pad bytes (0–46 bytes).

Figure 22. Flow of Frame Through the MAC RX With Preamble Pass-Through Turned On Illustrates the typical flow of frame through the MAC RX when the preamble pass-through feature is turned on. In this figure, <p> is payload size, and <s> is the number of pad bytes (0–46 bytes).

The following sections describe the functions performed by the RX MAC:

3.2.3.1. LL 40GbE IP Core RX Filtering

The LL 40GbE IP core processes all incoming valid frames. However, the IP core does not forward pause frames to the Avalon-ST RX client interface by default.

If you set the cfg_fwd_ctrl bit of the RX_PAUSE_FWD register to the value of 1, the IP core forwards pause frames to the Avalon-ST RX client interface.

3.2.3.2. LL 40GbE IP Core Preamble Processing

The preamble sequence is Start, six preamble bytes, and SFD. If this sequence is incorrect the frame is ignored. The Start byte must be on receive lane 0 (most significant byte). The IP core uses the SFD byte (0xD5) to identify the last byte of the preamble. The MAC RX looks for the Start, six preamble bytes and SFD.

By default, the MAC RX removes all Start, SFD, preamble, and IPG bytes from accepted frames. However, if you turn on Enable preamble passthrough in the LL 40GbE parameter editor, the MAC RX does not remove the eight-byte preamble sequence.

3.2.3.3. IP Core Strict SFD Checking

The LL 40GbE IP core RX MAC checks all incoming packets for a correct Start byte (0xFB). If you turn on Enable strict SFD checking in the LL 40GbE parameter editor, you enable the RX MAC to check the incoming preamble and SFD for the following values:

SFD = 0xD5
Preamble = 0x555555555555

The RX MAC checks one or both of these values depending on the values in bits [4:3] of the RXMAC_CONTROL register at offset 0x50A.

Table 19. Strict SFD Checking Configuration
Enable strict SFD checking	0x50A[4]: Preamble Check	0x50A[3]: SFD Check	Fields Checked	Behavior if Check Fails
Off	Don't Care	Don't Care	Start byte	IP core does not recognize a malformed Start byte as a Start byte
On	0	0	Start byte
	0	1	Start byte and SFD	IP Core drops the packet
	1	0	Start byte and preamble
	1	1	Start byte and preamble and SFD

3.2.3.4. LL 40GbE IP Core FCS (CRC-32) Removal

Independent user configuration register bits control FCS CRC removal at runtime. CRC removal supports both narrow and wide bus options. Bit 0 of the MAC_CRC_CONFIG register enables and disables CRC removal; by default, CRC removal is enabled.

In the user interface, the EOP signal (l4_rx_endofpacket or dout_eop ) indicates the end of CRC bytes if CRC is not removed. When CRC is removed, the EOP signal indicates the final byte of payload.

The IP core signals an FCS error by asserting the FCS error output signal l4_rx_fcs_error and the l4_rx_fcs_valid (or rx_fcs_error and the rx_fcs_valid) output signals in the same clock cycle. The l4_rx_error[1] or rx_error[1] also signals an FCS error.

If you turn on Enable alignment EOP on FCS word in the parameter editor, the IP core asserts l4_rx_fcs_error (or rx_fcs_error) and the EOP signal on the same clock cycle if the current frame has an FCS error. However, if you turn off Enable alignment EOP on FCS word , the IP core asserts l4_rx_fcs_error in a later clock cycle than the EOP signal.

3.2.3.5. LL 40GbE IP Core CRC Checking

The 32-bit CRC field is received in the order: X32, X30, . . . X1, and X0 , where X32 is the most significant bit of the FCS field and occupies the least significant bit position in the first FCS byte.

If a CRC32 error is detected, the RX MAC marks the frame invalid by asserting the l4_rx_fcs_error and l4_rx_fcs_valid (or rx_fcs_error and rx_fcs_valid) signals, as well as the l4_rx_error[1] (or rx_error[1]) signal.

3.2.3.6. LL 40GbE IP Core Malformed Packet Handling

While receiving an incoming packet from the Ethernet link, the LL 40GbE IP core expects to detect a terminate character at the end of the packet. When it detects an expected terminate character, the IP core generates an EOP on the client interface. However, sometimes the IP core detects an unexpected control character when it expects a terminate character. The LL 40GbE IP core detects and handles the following forms of malformed packets:

If the IP core detects an Error character, it generates an EOP, asserts a malformed packet error (rx_error[0] or l4_rx_error[0] ), and asserts an FCS error (rx_fcs_error (l4_rx_fcs_error ) and rx_error[1] (l4_rx_error[1] ). If the IP core subsequently detects a terminate character, it does not generate another EOP indication.
If the IP core detects any other control character when it is waiting for an EOP indication (terminate character), the IP core generates an EOP indication (for example, an IDLE or Start character), asserts a malformed packet error (rx_error[0] or l4_rx_error[0] ), and asserts an FCS error (rx_fcs_error (l4_rx_fcs_error ) and rx_error[1] (l4_rx_error[1] ). If the IP core subsequently detects a terminate character, it does not generate another EOP indication.

When the IP core receives a packet that contains an error deliberately introduced on the Ethernet link using the LL 40GbE TX error insertion feature, the IP core identifies it as a malformed packet.

3.2.3.7. RX CRC Forwarding

The CRC-32 field is forwarded to the client interface after the final byte of data, if the CRC removal option is not enabled.

3.2.3.8. Inter-Packet Gap

The MAC RX removes all IPG octets received, and does not forward them to the Avalon-ST client interface. If you configure your IP core with a custom streaming client interface, the MAC RX does not remove IPG octets. The MAC RX fowards all received IPG octets to the custom client interface.

3.2.3.9. Pause Ignore

If you turn on flow control by setting Flow control mode to the value of Standard flow control or Priority-based flow control in the LL 40GbE parameter editor, the IP core processes incoming pause frames by default. However, when the pause frame receive enable bit (for standard flow control) or bits (for priority-based flow control) is or are not set, the IP core does not process incoming pause frames. In this case, the MAC TX traffic is not affected by the valid pause frames.

If you turn off flow control by setting Flow control mode to the value of No flow control in the LL 40GbE parameter editor, the IP core does not process incoming pause frames.

3.2.3.10. Control Frame Identification

The mechanisms to process flow control frames from the Ethernet link are specific to the flow control mode of the LL 40GbE IP core. Therefore, control frames that are inappropriate to the IP core mode, simply pass through the RX MAC to the RX client interface.

If you turn off flow control by setting Flow control mode to the value of No flow control in the LL 40GbE parameter editor, the IP core might nevertheless receive a flow control request on the Ethernet link. Similarly, if you set Flow control mode to Standard flow control, the IP core might nevertheless receive a priority-based flow control request on the Ethernet link, and if you set Flow control mode to Priority-based flow control, the IP core might nevertheless receive a standard flow control request.

The IP core provides a three-bit RX status flag that identifies the control frames that appear on the RX client interface. The flag is one-hot encoded to identify whether the control frame is a standard flow control frame, a priority-based flow control frame, or a different type of control frame. If the flag has the value of 3'b000, the current packet on the RX client interface is not a control frame. You can use this flag to identify control frames on the RX client interface that the client prefers to ignore.

3.2.4. LL 40GbE IP Core RX Data Bus Interfaces

This section describes the RX data bus at the user interface and includes the following topics:

3.2.4.1. LL 40GbE IP Core User Interface Data Bus

The user interface width depends on your IP core variation. The LL 40GbE IP core provides two different client interfaces: the Avalon-ST interface and a custom interface.

Custom streaming interface (no adapters): Data bus width is 128 bits.
Avalon-ST interface: Data bus width is 256 bits.

Both interfaces operate at 312.5 MHz.

3.2.4.2. LL 40GbE IP Core RX Data Bus with Adapters (Avalon-ST Interface)

The LL 40GbE IP core RX datapath employs the Avalon-ST protocol. The Avalon-ST protocol is a synchronous point-to-point, unidirectional interface that connects the producer of a data stream (source) to a consumer of data (sink). The key properties of this interface include:

Start of packet (SOP) and end of packet (EOP) signals delimit frame transfers.
The SOP must always be in the MSB, simplifying the interpretation and processing of data you receive on this interface.
A valid signal qualifies signals from source to sink.

The RX MAC acts as a source and the client acts as a sink in the receive direction.

Figure 23. RX MAC to Client Interface

Table 20. Signals of the Avalon-ST RX Client InterfaceAll interface signals are clocked by the `clk_rxmac` clock.
Name	Direction	Description
`l4_rx_data[255:0]`	Output	RX data.
`l4_rx_empty[4:0]`	Output	Indicates the number of empty bytes on `l4_rx_data[255:0]` when `l4_rx_endofpacket` is asserted, starting from the least significant byte (LSB).
`l4_rx_startofpacket`	Output	When asserted, indicates the start of a packet. The packet starts on the MSB.
`l4_rx_endofpacket`	Output	When asserted, indicates the end of packet. In the case of an undersized packet, `l4_rx_startofpacket` and `l4_rx_endofpacket` could be asserted in the same clock cycle.
`l4_rx_error[5:0]`	Output	Reports certain types of errors in the Ethernet frame whose contents are currently being transmitted on the client interface. This signal is valid in EOP cycles only. To ensure you can identify the corresponding packet, you must turn on Enable alignment EOP on FCS word in the LL 40GbE parameter editor. The individual bits report different types of errors: Bit [0]: Malformed packet error. If this bit has the value of 1, the packet is malformed. The IP core identifies a malformed packet when it receives a control character that is not a terminate character, while receiving the packet. Bit [1]: CRC error. If this bit has the value of 1, the IP core detected a CRC error in the frame. If you turn on Enable alignment EOP on FCS word , this bit and the `l4_rx_fcs_error` signal behave identically. Bit [2]: undersized payload. If this bit has the value of 1, the frame size is between nine and 63 bytes, inclusive. The IP core does not recognize an incoming frame of size eight bytes or less as a frame, and those cases are not reported here. The `l4_rx_error[1]` bit also signals an FCS error. Bit [3]: oversized payload. If this bit has the value of 1, the frame size is greater than the maximum frame size programmed in the `MAX_RX_SIZE_CONFIG` register at offset 0x506. Bit [4]: payload length error. If this bit has the value of 1, the payload received in the frame did not match the length field value, and the value in the length field is less than 1536 bytes. This bit only reports errors if you set bit [0] of the `RXMAC_CONTROL` register at offset 0x50A to the value of 1. Bit [5]: Reserved.
`l4_rx_valid`	Output	When asserted, indicates that RX data is valid. Only valid between the `l4_rx_startofpacket` and `l4_rx_endofpacket` signals.
`l4_rx_fcs_valid`	Output	When asserted, indicates that FCS is valid.
`l4_rx_fcs_error`	Output	When asserted, indicates an FCS error condition. The IP core asserts the `l4_rx_fcs_error` signal only when it asserts the `l4_rx_fcs_valid` signal. Runt frames always force an FCS error condition. However, if a packet is eight bytes or smaller, it is considered a decoding error and not a runt frame, and the IP core does not flag it as a runt.
`l4_rx_status[2:0]`	Output	Indicates the IP core received a control frame on the Ethernet link. This signal identifies the type of control frame the IP core is passing through to the client interface. This signal is valid in EOP cycles only. To ensure you can identify the corresponding packet, you must turn on Enable alignment EOP on FCS word in the LL 40GbE parameter editor. The individual bits report different types of received control frames: Bit [0]: Indicates the IP core received a standard flow control frame. If the IP core is in standard flow control mode and the `cfg_fwd_ctrl` bit of the `RX_PAUSE_FWD` register has the value of 0, this bit maintains the value of 0. Bit [1]: Indicates the IP core received a priority flow control frame. If the IP core is in priority flow control mode and the `cfg_fwd_ctrl` bit of the `RX_PAUSE_FWD` register has the value of 0, this bit maintains the value of 0. Bit [2]: Indicates the IP core received a control frame that is not a flow control frame.

Figure 24. Traffic on the TX and RX Avalon-ST Client Interface for Low Latency 40GbE IP CoreShows typical traffic for the TX and RX Avalon-ST interface Low Latency 40GbE IP core.

3.2.4.3. LL 40GbE IP Core RX Data Bus Without Adapters (Custom Streaming Interface)

Figure 25. RX MAC to Client Interface Without Adapters

Table 21. Signals of the Custom Streaming RX Client InterfaceAll interface signals are clocked by the `clk_rxmac` clock.
Signal Name	Direction	Description
`dout_d[127:0]`	Output	Received data and Idle bytes. In RX preamble pass-through mode, this bus also carries the preamble.
`dout_c[15:0]`	Output	Indicates control bytes on the data bus. Each bit of dout_c indicates whether the corresponding byte of `dout_d` is a control byte. A bit is asserted high if the corresponding byte on `dout_d` is an Idle byte or the Start byte, and has the value of zero if the corresponding byte is a data byte or, in preamble pass-through mode, a preamble or SFD byte.
`dout_sop[1:0]`	Output	Indicates the first data word of a frame, in the current `clk_rxmac` cycle. In RX preamble pass-through mode, the first data word is the word that contains the preamble. When the RX preamble pass-through feature is turned off, the first data word is the first word of Ethernet data that follows the preamble. This signal is one-hot encoded.
`dout_eop[1:0]`	Output	Indicates the final word of a frame in the current `clk_rxmac` cycle. If CRC removal is disabled, this signal indicates the word with the final CRC byte. If CRC removal is enabled, this signal indicates the final word with data. This signal is one-hot encoded. In the case of an undersized packet, `dout_sop` and `dout_eop` might be non-zero in the same clock cycle.
`dout_eop_empty[5:0]`	Output	Indicates the number of empty (invalid) bytes in the end-of-packet 8-byte word indicated by `dout_eop`. If `dout_eop[z]` has the value of 0, then the IP core sets the value of `dout_eop_empty[(z+2):z]` to 0. However, if `dout_eop[z]` has the value of 1, then you must use the value of `dout_eop_empty[(z+2):z]` to determine the number of empty (invalid) bytes in the end-of-packet word (and therefore, the end-of-packet byte). For example, if you have a LL 40GbE IP core and you observe that in the current `clk_rxmac` clock cycle, `dout_eop` has the value of 2'b10 and `dout_eop_empty` has the value of 12'b110_000, you can conclude that byte 6 in word 2 of `dout_d` is an end-of-packet byte.
`dout_idle[1:0]`	Output	Indicates the words in `dout_d` that hold Idle bytes or control information rather than Ethernet data. This signal is one-hot encoded.
`rx_error[5:0]`	Output	Reports certain types of errors in the Ethernet frame whose contents are currently being transmitted on the client interface. This signal is valid in EOP cycles only. To ensure you can identify the corresponding packet, you must turn on Enable alignment EOP on FCS word in the LL 40GbE parameter editor. The individual bits report different types of errors: Bit [0]: Malformed packet error. If this bit has the value of 1, the packet is malformed. The IP core identifies a malformed packet when it receives a control character that is not a terminate character, while receiving the packet. Bit [1]: CRC error. If this bit has the value of 1, the IP core detected a CRC error in the frame. If you turn on Enable alignment EOP on FCS word , this bit and the `rx_fcs_error` signal behave identically. Bit [2]: undersized payload. If this bit has the value of 1, the frame size is between nine and 63 bytes, inclusive. The IP core does not recognize an incoming frame of size eight bytes or less as a frame, and those cases are not reported here. Bit [3]: oversized payload. If this bit has the value of 1, the frame size is greater than the maximum frame size programmed in the `MAX_RX_SIZE_CONFIG` register at offset 0x506. Bit [4]: payload length error. If this bit has the value of 1, the payload received in the frame did not match the length field value, and the value in the length field is less than 1536 bytes. This bit only reports errors if you set bit [0] of the `RXMAC_CONTROL` register at offset 0x50A to the value of 1. Bit [5]: Reserved.
`rx_fcs_error`	Output	The current or most recent EOP byte is part of a frame with an incorrect FCS (CRC-32) value. By default, the IP core asserts `rx_fcs_error` in the same cycle as the `dout_eop` signal. However, if you turn off Enable alignment EOP on FCS word in the LL 40GbE parameter editor, the `rx_fcs_error` signal might lag the `dout_eop` signal for the frame. Runt frames always force an FCS error condition. However, if a packet is eight bytes or smaller, it is considered a decoding error and not a runt frame, and the IP core does not flag it as a runt.
`rx_fcs_valid`	Output	When set, indicates that `rx_fcs_error` has a valid value in the current clock cycle.
`rx_status[2:0]`	Output	Indicates the IP core received a control frame on the Ethernet link. This signal identifies the type of control frame the IP core is passing through to the client interface. This signal is valid in EOP cycles only. To ensure you can identify the corresponding packet, you must turn on Enable alignment EOP on FCS word in the LL 40GbE parameter editor. The individual bits report different types of received control frames: Bit [0]: Indicates the IP core received a standard flow control frame. If the IP core is in standard flow control mode and the `cfg_fwd_ctrl` bit of the `RX_PAUSE_FWD` register has the value of 0, this bit maintains the value of 0. Bit [1]: Indicates the IP core received a priority flow control frame. If the IP core is in priority flow control mode and the `cfg_fwd_ctrl` bit of the `RX_PAUSE_FWD` register has the value of 0, this bit maintains the value of 0. Bit [2]: Indicates the IP core received a control frame that is not a flow control frame.
`dout_valid`	Output	The `dout_d` bus contents are valid. This signal is occasionally deasserted due to clock crossing.
`clk_rxmac`	Output	RX MAC clock. The clock frequency should be 312.5 MHz. The `clk_rxmac` clock is derived from the recovered CDR clock.

The data bytes use 100 Gigabit Media Independent Interface (CGMII-like) encoding. For packet payload bytes, the dout_c bit is set to 0 and the dout_d byte is the packet data. You can use this information to transmit out-of-spec data such as customized preambles when implementing non-standard variants of the IEEE 802.3ba-2010 High Speed Ethernet Standard.

In RX preamble pass-through mode, dout_c has the value of 1 while the start byte of the preamble is presented on the RX interface, and dout_c has the value of 0 while the remainder of the preamble sequence (six-byte preamble plus SFD byte) is presented on the RX interface.

3.2.5. External Reconfiguration Controller

LL 40GbE IP cores that target a Stratix^® V device require an external reconfiguration controller.

Intel recommends that you configure a Transceiver Reconfiguration Controller for your Stratix^® V LL 40GbE IP core.

3.2.6. External Transceiver PLL

LL 40GbE IP cores that target an Arria 10 device require an external transceiver PLL. The number and type of transceiver PLLs your design requires depends on the transceiver channels and available clock networks.

3.2.7. External TX MAC PLL

If you turn on Use external TX MAC PLL in the LL 40GbE parameter editor, the IP core has an extra input port, clk_txmac_in, which drives the TX MAC clock. You must connect this input port to a clock source, usually a PLL on the device.

The port is expected to receive the clock from the external TX MAC PLL and drives the internal clock clk_txmac. The required TX MAC clock frequency is 312.5 MHz . User logic must drive clk_txmac_in from a PLL whose input is the PHY reference clock, clk_ref.

3.2.8. Congestion and Flow Control Using Pause Frames

If you turn on flow control by setting Flow control mode to the value of Standard flow control or Priority-based flow control in the LL 40GbE parameter editor, the LL 40GbE IP core provides flow control to reduce congestion at the local or remote link partner. When either link partner experiences congestion, the respective transmit control sends pause frames. The pause frame instructs the remote transmitter to stop sending data for the duration that the congested receiver specified in an incoming XOFF frame. In the case of priority-based flow control, the pause frame applies to only the indicated priority class.

When the IP core receives the XOFF pause control frame, if the following conditions all hold, the IP core behavior depends on the flow control scheme.

In priority-based flow control, the IP core informs the TX client of the received XOFF frame. The IP core continues to process packets it receives on the TX client interface. The IP core tracks the pause quanta countdown internally and informs the TX client when the pause period is ended.
Note: In the priority-based flow control scheme, the client is responsible to throttle the flow of data to the TX client interface after the IP core informs the client of the received XOFF frame.
In standard flow control, the IP core TX MAC does not process TX packets and in fact, prevents the client from sending additional data to the TX client interface, for the duration of the pause quanta of the incoming pause frame.

The IP core responds to an incoming XOFF pause control frame if the following conditions all hold:

The relevant cfg_enable bit of the RX_PAUSE_ENABLE register has the value of 1.
In the case of standard flow control, bit [0] of the TX_XOF_EN register also has the value of 1.
Address matching is positive.

The pause quanta can be configured in the pause quanta register of the device sending XOFF frames. If the pause frame is received in the middle of a frame transmission, the transmitter finishes sending the current frame and then suspends transmission for a period specified by the pause quanta. Data transmission resumes when a pause frame with quanta of zero is received or when the timer has expired. The pause quanta received overrides any counter currently stored. When more than one pause quanta is sent, the value of the pause is set to the last quanta received.

XOFF pause frames stop the remote transmitter. XON pause frames let the remote transmitter resume data transmission.

One pause quanta fraction is equivalent to 512 bit times. The duration of a pause quantum is a function of the client interface datapath width (256 bits ) and the system clock (clk_txmac) frequency (312.5 MHz ).

Figure 26. The XOFF and XON Pause Frames for Standard Flow Control

XOFF Frame		XON Frame
START[7:0]		START[7:0]
PREAMBLE[47:0]		PREAMBLE[47:0]
SFD[7:0]		SFD[7:0]
DESTINATION ADDRESS[47:0] = 0x010000C28001 ¹		DESTINATION ADDRESS[47:0] = 0x010000C28001
SOURCE ADDRESS[47:0]		SOURCE ADDRESS[47:0]
TYPE[15:0] = 0x8808		TYPE[15:0] = 0x8808
OPCODE[15:0] = 0x001 (standard FC)		OPCODE[15:0] = 0x001 (standard FC)
PAUSE QUANTA[15:0] = 0xP1, 0xP2 ²		PAUSE QUANTA[15:0] = 0x0000
PAD[335:0]		PAD[335:0]
CRC[31:0]		CRC[31:0]

Figure 27. The XOFF and XON Pause Frames for Priority Flow Control

XOFF Frame		XON Frame
START[7:0]		START[7:0]
PREAMBLE[47:0]		PREAMBLE[47:0]
SFD[7:0]		SFD[7:0]
DESTINATION ADDRESS[47:0] = 0x010000C28001 ¹		DESTINATION ADDRESS[47:0] = 0x010000C28001
SOURCE ADDRESS[47:0]		SOURCE ADDRESS[47:0]
TYPE[15:0] = 0x8808		TYPE[15:0] = 0x8808
OPCODE[15:0] = 0x0101 (PFC)		OPCODE[15:0] = 0x0101 (PFC)
PRIORITY_ENABLE[15:0] ³		PRIORITY_ENABLE[15:0] ⁴
TIME0[15:0] ⁵		TIME0[15:0] = 0x0000
...		...
TIME7[15:0] ⁵		TIME7[15:0] = 0x0000
PAD[207:0]		PAD[207:0]
CRC[31:0]		CRC[31:0]

¹ This is a multicast destination address.

² The bytes P1 and P2 are filled with the value configured in the TX_PAUSE_QUANTA register.

³ Bit [n] has the value of 1 if the TIMEn field is valid.

⁴ Bit [n] has the value of 1 if the XON request applies to priority queue n.

⁵ The TIMEn field is filled with the value available in the TX_PAUSE_QUANTAregister when the TX_PAUSE_QNUMBER register holds the value of n.

3.2.8.1. Conditions Triggering XOFF Frame Transmission

The LL 40GbE IP core supports retransmission. In retransmission mode, the IP core retransmits a XOFF frame periodically, extending the pause time, based on signal values.

The TX MAC transmits XOFF frames when one of the following conditions occurs:

Client requests XOFF transmission—A client can explicitly request that XOFF frames be sent using the pause control interface signal. When pause_insert_tx is asserted, an XOFF frame is sent to the Ethernet network when the current frame transmission completes.
Host (software) requests XOFF transmission—Setting the pause request register triggers a request that an XOFF frame be sent.
Retransmission mode—If the retransmit hold-off enable bit has the value of 1, and the pause_insert_tx signal remains asserted or the pause request register value remains high, when the time duration specified in the hold-off quanta register has lapsed after the previous XOFF transmission, the TX MAC sends another XOFF frame to the Ethernet network. While the IP core is paused in retransmission mode, you cannot use either of the other two methods to trigger a new XOFF frame: the signal or register value is already high.

Note: Intel recommends that you use the pause_insert_tx signal to backpressure the remote Ethernet node.

Note: Intel recommends that you set and maintain the value of the retransmit hold-off enable bit at 1 to control the rate of XOFF pause frame transmission.

3.2.8.2. Conditions Triggering XON Frame Transmission

The TX MAC transmits XON frames when one of the following conditions occurs:

Client requests XON transmission—A client can explicitly request that XON frames be sent using the pause control interface signal. When pause_insert_tx is de-asserted, an XON frame is sent to the Ethernet network when the current frame transmission completes.
Host (software) requests XON transmission—Resetting the pause request register triggers a request that an XON frame be sent.

3.2.9. Pause Control and Generation Interface

The pause control interface implements flow control as specified by the IEEE 802.3ba 2010 High Speed Ethernet Standard. If you turn on priority-based flow control, the interface implements the IEEE Standard 802.1Qbb. The pause logic, upon receiving a pause packet, temporarily stops packet transmission, and can pass the pause packets through as normal traffic or drop the pause control frames in the RX direction.

Table 22. Pause Control and Generation SignalsDescribes the signals that implement pause control. These signals are available only if you turn on flow control in the LL 40GbE parameter editor.
Signal Name	Direction	Description
`pause_insert_tx[N-1:0]` ⁶	Input	Level signal which directs the IP core to insert a pause frame for priority traffic class [n] on the Ethernet link. If bit [n] of the `TX_PAUSE_EN` register has the value of 1, the IP core transmits an XOFF frame when this signal is first asserted. If you enable retransmission, the IP core continues to transmit XOFF frames periodically until the signal is de-asserted. When the signal is deasserted, the IP core inserts an XON frame.
`pause_receive_rx[N-1:0]` ⁶	Output	Asserted to indicate an RX pause signal match. The IP core asserts bit [n] of this signal when it receives a pause request with an address match, to signal the TX MAC to throttle its transmissions from priority queue [n] on the Ethernet link.

⁶ N is the number of priority queues. If the IP core implements Ethernet standard flow control, N is 1.

3.2.10. Pause Control Frame Filtering

The LL 40GbE IP core supports options to enable or disable the following features for incoming pause control frames. These options are available if you set the Flow control mode parameter to the value of Standard flow control or Priority-based flow control.

Processing—You can enable or disable pause frame processing. If you disable pause frame processing, the IP core does not modify its behavior in response to incoming pause frames on the Ethernet link. You can enable or disable pause frame processing with the cfg_enable bit of the RX_PAUSE_ENABLE register. By default, RX pause frame processing is enabled.
Note: IP core variations that target an Arria 10 device do not process standard pause frames that are runts or have FCS errors, for any setting of the cfg_enable bit of the RX_PAUSE_ENABLE register.
Filtering—If pause frame processing is enabled, the IP core automatically performs address filtering on incoming pause control frames before processing them. You set the matching address value in these registers:
- RX_PAUSE_DADDRL[31:0] at offset 0x707
- RX_PAUSE_DADDRH[15:0] at offset 0x708
The 48-bit address ({RX_PAUSE_DADDRH[15:0],RX_PAUSE_DADDRL[31:0]} can be an individual MAC address, a multicast address, or a broadcast address.
TX MAC filtering—For standard flow control only, Intel provides an additional level of filtering to enable or disable the TX MAC from responding to notification from the RX MAC that it received an incoming pause frame with an address match. Even if the RX MAC processes an incoming pause frame, you can separately set the TX MAC to ignore the RX MAC request to pause outgoing frames, by setting bit [0] of the TX_XOF_EN register to the value of 0. By default this register field has the value of 1.
Pass-through—The LL 40GbE IP core can pass the matching pause packets through as normal traffic or drop these pause control frames in the RX direction. You can enable and disable pass-through with the cfg_fwd_ctrl bit of the RX_PAUSE_FWD register. By default, pass-through is disabled. All non-matching pause frames are passed through to the RX client interface irrespective of the cfg_fwd_ctrl setting.

The following rules define pause control frames filtering control:

If you have disabled pause frame processing, by setting the cfg_enable bit of the RX_PAUSE_ENABLE register to the value of 0, the IP core drops packets that enter the RX MAC and match the destination address, length, and type of 0x8808 with an opcode of 0x1 (pause packets).
Note: IP core variations that target an Arria 10 device do not process standard Ethernet pause frames that are runts or have FCS errors.
If you have enabled pause frame processing, and the destination address in the pause frame is a match, when the RX MAC receives a pause packet it passes a pause request to the TX MAC. The RX MAC only processes pause packets with a valid packet multicast address or a destination address matching the destination address specified in the RX_PAUSE_DADDR1 and RX_PAUSE_DADDR0 registers, or in the RX_PAFC_DADDRH and RX_PFC_DADDRL registers, as appropriate for the flow control mode . If you have turned on pause frame pass-through, the RX MAC also forwards the pause frame to the RX client interface. If you have not turned on pause frame pass-through, the RX MAC does not forward the matching pause frame to the RX client interface.
In priority-based flow control, or in standard flow control if you have enabled TX MAC filtering, when the TX MAC receives a pause request from the RX MAC, it pauses transmission on the TX Ethernet link.

Pause packet pass-through does not affect the pause functionality in the TX or RX MAC. Pass-through applies equally to pause control frames that are runts or have FCS errors.

3.2.11. Link Fault Signaling Interface

If you turn on Enable link fault generation in the LL 40GbE parameter editor, the LL 40GbE IP core provides link fault signaling as defined in the IEEE 802.3ba-2010 High Speed Ethernet Standard and Clause 66 of the IEEE 802.3-2012 Ethernet Standard, based on the LINK_FAULT_CONFIG register settings. The LL 40GbE MAC includes a Reconciliation Sublayer (RS) located between the MAC and the XLGMII or CGMII to manage local and remote faults. Link fault signaling on the Ethernet link is disabled by default but can be enabled by bit [0] of the LINK_FAULT_CONFIG register. When the LINK_FAULT_CONFIG register bits [1:0] have the value of 2'b01, link fault signaling is enabled in normal bidirectional mode. In this mode, the local RS TX logic transmits remote fault sequences in case of a local fault and transmits IDLE control words in case of a remote fault.

If you turn on bit [1] of the LINK_FAULT_CONFIG register, the IP core conforms to Clause 66 of the IEEE 802.3-2012 Ethernet Standard. When LINK_FAULT_CONFIG[1:0] has the value of 2'b11, the IP core transmits the fault sequence ordered sets in the interpacket gaps according to the clause requirements.

The RS RX logic sets remote_fault_status or local_fault_status to 1 when the RS RX block receives remote fault or local fault sequence ordered sets. When valid data is received in more than 127 columns, the RS RX logic resets the relevant fault status (remote_fault_status or local_fault_status) to 0.

The IEEE standard specifies RS monitoring of RXC<7:0> and RXD<63:0> for Sequence ordered_sets. For more information, refer to Figure 81–9—Link Fault Signaling state diagram and Table 81-5—Sequence ordered_sets in the IEEE 802.3ba 2010 High Speed Ethernet Standard. The variable link_fault is set to indicate the value of an RX Sequence ordered_set when four fault_sequences containing the same fault value are received with fault sequences separated by less than 128 columns and with no intervening fault_sequences of different fault values. The variable link_fault is set to OK following any interval of 128 columns not containing a remote fault or local fault Sequence ordered_set.

Table 23. Signals of the Link Fault Signaling InterfaceThese signals are available only if you turn on Enable link fault generation in the LL 40GbE parameter editor.
Signal Name	Direction	Description
`remote_fault_status`	Output	Asserted by the IP core when it detects a real-time remote fault in the RX MAC. The IP core asserts this signal regardless of the settings in the `LINK_FAULT_CONFIG` register. This signal is clocked by `clk_rxmac`.
`local_fault_status`	Output	Asserted by the IP core when it detects a real-time local fault in the RX MAC. The IP core asserts this signal regardless of the settings in the `LINK_FAULT_CONFIG` register. This signal is clocked by `clk_rxmac`.
`unidirectional_en`	Output	The IP core asserts this signal if it includes Clause 66 support for remote link fault reporting on the Ethernet link. Connects to the `Unidir Enable` field in bit [1] of the `LINK_FAULT_CONFIG` register at offset 0x405. This signal is clocked by `clk_txmac`.
`link_fault_gen_en`	Output	The IP core asserts this signal if the PCS is enabled to generate a remote fault sequence on the Ethernet link when appropriate. Connects to the `Link Fault Reporting Enable` field in bit [0] of the `LINK_FAULT_CONFIG` register at offset 0x405. This signal is clocked by `clk_txmac`.

3.2.12. Statistics Counters Interface

The statistics counters modules are synthesis options that you select in the LL 40GbE parameter editor. However, the statistics status bit output vectors are provided whether you select the statistics counters module option or not.

The increment vectors are brought to the top level as output ports. The increment vectors also function internally as input ports to the control and status registers (CSR).

Table 24. Statistics Counters Increment Vectors The TX statistics counter increment vectors are clocked by the `clk_txmac` clock, and the RX statistics counter increment vectors are clocked by the `clk_rxmac` clock.
Name	Signal Direction	Description
TX Statistics Counter Increment Vectors
`tx_inc_64`	Output	Asserted for one cycle when a 64-byte TX frame is transmitted.
`tx_inc_127`	Output	Asserted for one cycle when a 65–127 byte TX frame is transmitted.
`tx_inc_255`	Output	Asserted for one cycle when a 128–255 byte TX frame is transmitted.
`tx_inc_511`	Output	Asserted for one cycle when a 256–511 byte TX frame is transmitted.
`tx_inc_1023`	Output	Asserted for one cycle when a 512–1023 byte TX frame is transmitted.
`tx_inc_1518`	Output	Asserted for one cycle when a 1024–1518 byte TX frame is transmitted.
`tx_inc_max`	Output	Asserted for one cycle when a maximum-size TX frame is transmitted. You program the maximum number of bytes in the `MAX_TX_SIZE_CONFIG` register.
`tx_inc_over`	Output	Asserted for one cycle when an oversized TX frame is transmitted. You program the maximum number of bytes in the `MAX_TX_SIZE_CONFIG` register.
`tx_inc_mcast_data_err`	Output	Asserted for one cycle when an errored multicast TX frame, excluding control frames, is transmitted.
`tx_inc_mcast_data_ok`	Output	Asserted for one cycle when a valid multicast TX frame, excluding control frames, is transmitted.
`tx_inc_bcast_data_err`	Output	Asserted for one cycle when an errored broadcast TX frame, excluding control frames, is transmitted.
`tx_inc_bcast_data_ok`	Output	Asserted for one cycle when a valid broadcast TX frame, excluding control frames, is transmitted.
`tx_inc_ucast_data_err`	Output	Asserted for one cycle when an errored unicast TX frame, excluding control frames, is transmitted.
`tx_inc_ucast_data_ok`	Output	Asserted for one cycle when a valid unicast TX frame, excluding control frames, is transmitted.
`tx_inc_mcast_ctrl`	Output	Asserted for one cycle when a valid multicast TX frame is transmitted.
`tx_inc_bcast_ctrl`	Output	Asserted for one cycle when a valid broadcast TX frame is transmitted.
`tx_inc_ucast_ctrl`	Output	Asserted for one cycle when a valid unicast TX frame is transmitted.
`tx_inc_pause`	Output	Asserted for one cycle when a valid pause TX frame is transmitted.
`tx_inc_fcs_err`	Output	Asserted for one cycle when a TX packet with FCS errors is transmitted.
`tx_inc_fragment`	Output	Asserted for one cycle when a TX frame less than 64 bytes and reporting a CRC error is transmitted.
`tx_inc_jabber`	Output	Asserted for one cycle when an oversized TX frame reporting a CRC error is transmitted.
`tx_inc_sizeok_fcserr`	Output	Asserted for one cycle when a valid TX frame with FCS errors is transmitted.
RX Statistics Counter Increment Vectors
`rx_inc_runt`	Output	Asserted for one cycle when an RX runt packet is received.
`rx_inc_64`	Output	Asserted for one cycle when a 64-byte RX frame is received.
`rx_inc_127`	Output	Asserted for one cycle when a 65–127 byte RX frame is received.
`rx_inc_255`	Output	Asserted for one cycle when a 128–255 byte RX frame is received.
`rx_inc_511`	Output	Asserted for one cycle when a 256–511 byte RX frame is received.
`rx_inc_1023`	Output	Asserted for one cycle when a 512–1023 byte RX frame is received.
`rx_inc_1518`	Output	Asserted for one cycle when a 1024–1518 byte RX frame is received.
`rx_inc_max`	Output	Asserted for one cycle when a maximum-size RX frame is received. You program the maximum number of bytes in the `MAX_RX_SIZE_CONFIG` register.
`rx_inc_over`	Output	Asserted for one cycle when an oversized RX frame is received. You program the maximum number of bytes in the `MAX_RX_SIZE_CONFIG` register.
`rx_inc_mcast_data_err`	Output	Asserted for one cycle when an errored multicast RX frame, excluding control frames, is received.
`rx_inc_mcast_data_ok`	Output	Asserted for one cycle when valid a multicast RX frame, excluding control frames, is received.
`rx_inc_bcast_data_err`	Output	Asserted for one cycle when an errored broadcast RX frame, excluding control frames, is received.
`rx_inc_bcast_data_ok`	Output	Asserted for one cycle when a valid broadcast RX frame, excluding control frames, is received.
`rx_inc_ucast_data_err`	Output	Asserted for one cycle when an errored unicast RX frame, excluding control frames, is received.
`rx_inc_ucast_data_ok`	Output	Asserted for one cycle when a valid unicast RX frame, excluding control frames, is received.
`rx_inc_mcast_ctrl`	Output	Asserted for one cycle when a valid multicast RX frame is received.
`rx_inc_bcast_ctrl`	Output	Asserted for one cycle when a valid broadcast RX frame is received.
`rx_inc_ucast_ctrl`	Output	Asserted for one cycle when a valid unicast RX frame is received.
`rx_inc_pause`	Output	Asserted for one cycle when valid RX pause frames are received.
`rx_inc_fcs_err`	Output	Asserted for one cycle when a RX packet with FCS errors is received.
`rx_inc_fragment`	Output	Asserted for one cycle when a RX frame less than 64 bytes and reporting a CRC error is received.
`rx_inc_jabber`	Output	Asserted for one cycle when an oversized RX frame reporting a CRC error is received.
`rx_inc_sizeok_fcserr`	Output	Asserted for one cycle when a valid RX frame with FCS errors is received.
`rx_inc_pause_ctrl_err`	Output	Asserted for one cycle when an errored pause RX frame is received.
`rx_inc_mcast_ctrl_err`	Output	Asserted for one cycle when an errored multicast RX control frame is received.
`rx_inc_bcast_ctrl_err`	Output	Asserted for one cycle when an errored broadcast RX control frame is received.
`rx_inc_ucast_ctrl_err`	Output	Asserted for one cycle when an errored unicast RX control frame is received.

3.2.12.1. OctetOK Count Interface

The statistics counters include two 64-bit counters, RxOctetsOK and TxOctetsOK, which count the payload bytes (octets) in frames with no FCS, undersized, oversized, or payload length errors. The RxOctetsOK register maintains a cumulative count of the payload bytes in the qualifying received frames, and complies with section 5.2.1.14 of the IEEE Standard 802.3-2008. The TxOctetsOK register maintains a cumulative count of the payload bytes in the qualifying transmitted frames, and complies with section 5.2.2.18 of the IEEE Standard 802.3-2008.

To support payload size checking per frame, the LL 40GbE IP core provides an octetOK count interface instead of standard increment vectors. For most purposes, the number of payload bytes per frame is of more interest than the cumulative count, and an increment vector that pulses when the counter increments would be difficult to track. For each of these two registers, the IP core maintains two signals. A 16-bit signal provides a count of the payload bytes in the current frame, and the other signal pulses to indicate when the first signal is valid. The per-frame count is valid only when the valid signal is asserted. All signals in this interface are functional even if you do not turn on the corresponding statistics module.

Table 25. OctetOK Count Interface SignalsThe signals for received frames are clocked by the `clk_rxmac` clock. The signals for transmitted frames are clocked by the `clk_txmac` clock.
Name	Signal Direction	Description
`tx_inc_octetsOK[15:0]`	Output	When `tx_inc_octetsOK_valid` is asserted, `tx_inc_octetsOK[15:0]` holds the count of payload bytes in the current valid frame.
`tx_inc_octetsOK_valid`	Output	Pulses to indicate that `tx_inc_octetsOK[15:0]` currently holds the number of payload bytes for the current transmitted frame, and that the current frame is a qualifying frame. A qualifying frame has no FCS errors, no oversized error, no undersized error, and no payload length error.
`rx_inc_octetsOK[15:0]`	Output	When `rx_inc_octetsOK_valid` is asserted, `rx_inc_octetsOK[15:0]` holds the count of payload bytes in the current valid frame.
`rx_inc_octetsOK_valid`	Output	Pulses to indicate that `rx_inc_octetsOK[15:0]` currently holds the number of payload bytes for the current received frame, and that the current frame is a qualifying frame. A qualifying frame has no FCS errors, no oversized error, no undersized error, and no payload length error.

3.2.13. 1588 Precision Time Protocol Interfaces

If you turn on Enable 1588 PTP , the LL 40GbE core processes and provides 1588 Precision Time Protocol (PTP) timestamp information as defined in the IEEE 1588-2008 Precision Clock Synchronization Protocol for Networked Measurement and Control Systems Standard. This feature supports PHY operating speed with a timestamp accuracy of ± 7 ns .

1588 PTP packets carry timestamp information. The LL 40GbE core updates the incoming timestamp information in a 1588 PTP packet to transmit a correct updated timestamp with the data it transmits on the Ethernet link, using a one-step or two-step clock.

A fingerprint can accompany a 1588 PTP packet. You can use this information for client identification and other client uses. If provided fingerprint information, the IP core passes it through unchanged.

The IP core connects to a time-of-day (TOD) module that continuously provides the current time of day based on the input clock frequency. Because the module is outside the LL 40GbE core, you can use the same module to provide the current time of day for multiple modules in your system.

3.2.13.1. Implementing a 1588 System That Includes a LL 40GbE Core

The 1588 specification in IEEE 1588-2008 Precision Clock Synchronization Protocol for Networked Measurement and Control Systems Standard describes various systems you can implement in hardware and software to synchronize clocks in a distributed system by communicating offset and frequency correction information between master and slave clocks in arbitrarily complex systems. A 1588 system that includes the LL 40GbE core with 1588 PTP functionality uses the incoming and outgoing timestamp information from the IP core and the other modules in the system to synchronize clocks across the system.

The LL 40GbE core with 1588 PTP functionality provides the timestamp manipulation and basic update capabilities required to integrate your IP core in a 1588 system. You can specify that packets are PTP packets, and how the IP core should update incoming timestamps from the client interface before transmitting them on the Ethernet link. The IP core does not implement the event messaging layers of the protocol, but rather provides the basic hardware capabilities that support a system in implementing the full 1588 protocol.

Figure 28. Example Ethernet System with Ordinary Clock Master and Ordinary Clock SlaveYou can implement both master and slave clocks using the LL 40GbE core with 1588 PTP functionality.

Figure 29. Hardware Configuration Example Using LL 40GbE core in a 1588 System in Transparent Clock Mode

Figure 30. Software Flow Using Transparent Clock Mode SystemThis figure from the 1588 standard is augmented with the timestamp labels shown in the transparent clock system figure. A precise description of the software requirements is beyond the scope of this document. Refer to the 1588 standard.

Figure 31. Example Boundary Clock with One Slave Port and Two Master PortsYou can implement a 1588 system in boundary clock mode using the LL 40GbE core with 1588 PTP functionality.

3.2.13.2. PTP Receive Functionality

If you turn on Enable 1588 PTP in the LL 40GbE parameter editor, the IP core provides a 96-bit (V2 format) or 64-bit timestamp with every packet on the RX client interface, whether it is a 1588 PTP packet or not. The value on the timestamp bus (rx_ingress_timestamp_96b_data[95:0] or rx_ingress_timestamp_64b_data[63:0] or both, if present) is valid in the same clock cycle as the RX SOP signal. The value on the timestamp bus is not the current timestamp; instead, it is the timestamp from the time when the IP core received the packet on the Ethernet link. The IP core captures the time-of-day from the TOD module on rx_time_of_data_96b_data or rx_time_of_day_64b_data at the time it receives the packet on the Ethernet link, and sends that timestamp to the client on the RX SOP cycle on the timestamp bus rx_ingress_timestamp_96b_data[95:0] or rx_ingress_timestamp_64b_data[63:0] or both, if present. User logic can use this timestamp or ignore it.

Figure 32. PTP Receive Block Diagram

3.2.13.3. PTP Transmit Functionality

When you send a 1588 PTP packet to a LL 40GbE core with Enable 1588 PTP turned on in the parameter editor, you should assert the following respective input signals with the TX SOP signal to tell the IP core the PTP operations or processes that the IP core should perform to the packet:

tx_egress_timestamp_request_valid: assert this signal to tell the IP core to process the current packet in two-step processing mode.
tx_etstamp_ins_ctrl_timestamp_insert: assert this signal to tell the IP core to process the current packet in one-step processing mode and to insert the exit timestamp for the packet in the packet (insertion mode).
tx_etstamp_ins_ctrl_residence_time_update: assert this signal to tell the IP core to process the current packet in one-step processing mode and to update the timestamp in the packet by adding the latency through the IP core (the residence time in the IP core) to the cumulative delay field maintained in the packet (correction mode). This mode supports transparent clock systems.

Note: If tx_etstamp_ins_ctrl_residence_time_update is asserted, you should not assert tx_egress_timestamp_request_valid or tx_etstamp_ins_ctrl_timestamp_insert as the result will be undefined.

The IP core transmits the 1588 PTP packet in an Ethernet frame after PTP processing.

Figure 33. PTP Transmit Block Diagram

In one-step mode, the IP core either overwrites the timestamp information provided at the user-specified offset with the packet exit timestamp (insertion mode), or adds the residence time in this system to the value at the specified offset (correction mode). You tell the IP core how to process the timestamp by asserting the appropriate signal with the TX SOP signal. You must specify the offset of the timestamp in the packet (tx_etstamp_ins_ctrl_offset_timestamp) in insertion mode, or the offset of the correction field in the packet (tx_etstamp_ins_ctrl_offset_correction_field) in correction mode. In addition, the IP core zeroes out or updates the UDP checksum, or leaves the UDP checksum as is, depending on the mutually exclusive tx_etstamp_ins_ctrl_checksum_zero and tx_etstamp_ins_ctrl_checksum_correct signals.

Two-step PTP processing ignores the values on the one-step processing signals. In two-step processing mode, the IP core does not modify the current timestamp in the packet. Instead, the IP core transmits a two-step derived timestamp on the separate tx_egress_timestamp_96b_data[95:0] or tx_egress_timestamp_64b_data[63:0] bus, when it begins transmitting the Ethernet frame. The value on the tx_egress_timestamp_{96b,64b}_data bus is the packet exit timestamp. The tx_egress_timestamp_{96b,64b}_data bus holds a valid value when the corresponding tx_egress_timestamp_{96b,64b}_valid signal is asserted.

In addition, to help the client to identify the packet, you can specify a fingerprint to be passed by the IP core in the same clock cycle with the timestamp. To specify the number of distinct fingerprint values the IP core can handle, set the Timestamp fingerprint width parameter to the desired number of bits W. You provide the fingerprint value to the IP core in the tx_egress_timestamp_request_fingerprint[(W–1):0] signal. The IP core then drives the fingerprint on the appropriate tx_egress_timestamp_{96b,64b}_fingerprint[(W–1):0] port with the corresponding output timestamp, when it asserts the tx_egress_timestamp_{96b,64b}_valid signal.

The IP core calculates the packet exit timestamp.

exit TOD = entry TOD + IP core maintained expected latency + user-specified extra latency

entry TOD is the value in tx_time_of_day_96b_data or tx_time_of_day_64b_data when the packet enters the IP core.
The expected latency through the IP core is a static value. The IP core maintains this value internally.
The IP core reads the user-specified extra latency from the TX_PTP_EXTRA_LATENCY register. This option is provided for user flexibility.

The IP core provides the exit TOD differently in different processing modes.

In two-step mode, the IP core drives the exit TOD on tx_egress_timestamp_96b_data and on tx_egress_timestamp_64b_data, as available.
In one-step processing insertion mode, the IP core inserts the exit TOD in the timestamp field of the packet at the offset you specify in tx_etstamp_ins_ctrl_offset_timestamp.
In one-step processing correction mode, the IP core calculates the exit TOD and uses it only to calculate the residence time.

In one-step processing correction mode, the IP core calculates the updated correction field value:

exit correction field value = entry correction field value + residence time + asymmetry extra latency

residence time = exit TOD – entry (ingress) timestamp.
entry (ingress) timestamp is the value on tx_etstamp_ins_ctrl_ingress_timestamp_{95,64}b in the SOP cycle when the IP core received the packet on the TX client interface. The application is responsible to drive this signal with the correct value for the cumulative calculation. The correct value depends on system configuration.
The IP core reads the asymmetry extra latency from the TX_PTP_ASYM_DELAY register if the tx_egress_asymmetry_update signal is asserted. This option is provided for additional user-defined precision. You can set the value of this register and set the tx_egress_asymmetry_update signal to indicate the register value should be included in the latency calculation.

3.2.13.4. External Time-of-Day Module for 1588 PTP Variations

LL 40GbE cores that include the 1588 PTP module require an external time-of-day (TOD) module to provide the current time-of-day in each clock cycle, based on the incoming clock. The TOD module must update the time-of-day output value on every clock cycle, and must provide the TOD value in the V2 format (96 bits) or the 64-bit TOD format, or both.

3.2.13.5. PTP Timestamp and TOD Formats

The LL 40GbE core supports a 96-bit timestamp (V2 format) or a 64-bit timestamp (correction-field format) in PTP packets. The 64-bit timestamp and TOD signals of the IP core are in an Intel-defined 64-bit format that is distinct from the V1 format, for improved efficiency in one-step processing correction mode. Therefore, if your system need not handle any packets in one-step processing correction mode, you should turn off the Enable 64b Time of Day Format parameter .

You control the format or formats the IP core supports with the Enable 64b Time of Day Format and Enable 96b Time of Day Format parameters . If you turn on Enable 96b Time of Day Format , your IP core can support two-step processing mode, one-step processing insertion mode, and one-step processing correction mode, and can support both V1 and V2 formats. You can turn on Enable 64b Time of Day Format and turn off Enable 96b Time of Day Format to support one-step processing correction mode more efficiently. However, if you do so, your IP core variation cannot support two-step processing mode and cannot support one-step processing insertion mode. If you turn on both of these parameters, the value you drive on the tx_estamp_ins_ctrl_timestamp_format or tx_etstamp_ins_ctrl_residence_time_calc_format signal determines the format the IP core supports for the current packet.

The IP core completes all internal processing in the V2 format. However, if you specify V1 format for a particular PTP packet in one-step insertion mode, the IP core inserts the appropriate V1-format timestamp in the outgoing packet on the Ethernet link.

V2 Format

The IP core maintains the time-of-day (TOD) in V2 format according to the IEEE specification:

Bits [95:48]: Seconds (48 bits).
Bits [47:16]: Nanoseconds (32 bits). This field overflows at 1 billion.
Bits [15:0]: Fractions of nanosecond (16 bits). This field is a true fraction; it overflows at 0xFFFF.

The IP core can receive time-of-day information from the TOD module in V2 format or in 64-bit TOD format, or both, depending on your settings for the Enable 64b Time of Day Format and Enable 96b Time of Day Format parameters .

V1 Format

V1 timestamp format is specified in the IEEE specification:

Bits [63:32]: Seconds (32 bits).
Bits [31:0]: Nanoseconds (32 bits). This field overflows at 1 billion.

Intel 64-Bit TOD Format

The Intel 64-bit TOD format is distinct from the V1 format and supports a longer time delay. It is intended for use in transparent clock systems, in which each node adds its own residence time to a running total latency through the system. This format matches the format of the correction field in the packet, as used in transparent clock mode.

Bits [63:16]: Nanoseconds (48 bits). This field can specify a value greater than 4 seconds.
Bits [15:0]: Fractions of nanosecond (16 bits). This field is a true fraction; it overflows at 0xFFFF.

The TOD module provides 64-bit TOD information to the IP core in this 64-bit TOD format. The expected format of all 64-bit input timestamp and TOD signals to the IP core is the Intel 64-bit TOD format. The format of all 64-bit output timestamp and TOD signals from the IP core is the Intel 64-bit TOD format. If you build your own TOD module that provides 64-bit TOD information to the IP core, you must ensure it provides TOD information in the Intel 64-bit TOD format.

3.2.13.6. 1588 PTP Interface Signals

Table 26. Signals of the 1588 Precision Time Protocol InterfaceSignals are clocked by `clk_rxmac` or `clk_txmac`, as specified. All 64-bit output signals are in the Intel 64-bit TOD format, and you are expected to drive all 64-bit input signals in this format.
Signal Name	Direction	Description
PTP Interface to TOD module
`tx_time_of_day_96b_data[95:0]`	Input	Current V2-format (96-bit) TOD in `clk_txmac` clock domain. Connect this signal to the external TOD module. This signal is available only if you turn on the Enable 96b Time of Day Format parameter.
`tx_time_of_day_64b_data[63:0]`	Input	Current 64-bit TOD in `clk_txmac` clock domain. Connect this signal to the external TOD module. This signal is available only if you turn on the Enable 64b Time of Day Format parameter.
`rx_time_of_day_96b_data[95:0]`	Input	Current V2-format (96-bit) TOD in `clk_rxmac` clock domain. Connect this signal to the external TOD module. This signal is available only if you turn on the Enable 96b Time of Day Format parameter.
`rx_time_of_day_64b_data[63:0]`	Input	Current 64-bit TOD in `clk_rxmac` clock domain. Connect this signal to the external TOD module. This signal is available only if you turn on the Enable 64b Time of Day Format parameter.
PTP Interface to Client
TX Signals Related to One Step Processing
`tx_etstamp_ins_ctrl_timestamp_insert`	Input	Indicates the current packet on the TX client interface is a 1588 PTP packet, and directs the IP core to process the packet in one-step processing insertion mode. In this mode, the IP core overwrites the timestamp of the packet with the timestamp field when the packet appears on the TX Ethernet link. The TX client must assert and deassert this signal synchronously with the TX SOP signal for the 1588 PTP packet. If the TX client asserts this signal simultaneously with either of `tx_etstamp_ins_ctrl_residence_time_update` or `tx_egress_timestamp_request_valid` , the results are undefined.
`tx_etstamp_ins_ctrl_residence_time_update`	Input	Indicates the current packet on the TX client interface is a 1588 PTP packet, and directs the IP core to process the packet in one-step processing correction mode. In this mode, the IP core adds the latency through the IP core (residence time) to the current contents of the timestamp field. The TX client must assert and deassert this signal synchronously with the TX SOP signal for the 1588 PTP packet. If the TX client asserts this signal simultaneously with either of `tx_etstamp_ins_ctrl_timestamp_insert` or `tx_egress_timestamp_request_valid`, the results are undefined.
`tx_etstamp_ins_ctrl_ingress_timestamp_96b[95:0]`	Input	Iindicates the V2-format TOD when the packet entered the system. The TX client must ensure this signal is valid in each TX SOP cycle when it asserts `tx_etstamp_ins_ctrl_residence_time_update`. The TX client must maintain the desired value on this signal while the TX SOP signal is asserted. This signal is useful only in transparent clock mode when the TX client asserts `tx_etstamp_ins_ctrl_residence_time_update`. This signal is available only if you turn on the Enable 96b Time of Day Format parameter.
`tx_etstamp_ins_ctrl_ingress_timestamp_64b[63:0]`	Input	Indicates the TOD (in Intel 64-bit format) when the packet entered the system. The TX client must ensure this signal is valid in each TX SOP cycle when it asserts `tx_etstamp_ins_ctrl_residence_time_update`. The TX client must maintain the desired value on this signal while the TX SOP signal is asserted. This signal is useful only in transparent clock mode when the TX client asserts `tx_etstamp_ins_ctrl_residence_time_update`. This signal is available only if you turn on the Enable 64b Time of Day Format parameter.
`tx_etstamp_ins_ctrl_timestamp_format`	Input	Specifies the timestamp format (V1 or V2 format) for the current packet if the TX client simultaneously asserts `tx_etstamp_ins_ctrl_timestamp_insert`. Values are: 1'b0: 96-bit timestamp format (V2) 1'b1: 64-bit timestamp format (V1) The TX client must maintain the desired value on this signal while the TX SOP signal is asserted. If the client specifies the V1 format, you read and write the V1 format TOD (32 bits of seconds and 32 bits of nanoseconds) in bits [79:16] of the 96-bit timestamp and TOD signals. Note: If you do not turn on the Enable 96b Time of Day Format parameter, the results of asserting `tx_etstamp_ins_ctrl_timestamp_insert` are undefined. Therefore, the timestamp in either case maps to the 96-bit signals.
`tx_etstamp_ins_ctrl_residence_time_calc_format`	Input	Specifies the TOD format (Intel 64-bit TOD format or the V2 96-bit format) for the current packet if the TX client simultaneously asserts `tx_etstamp_ins_ctrl_residence_time_update`. Values are: 1'b0: 96-bit TOD format (V2) 1'b1: 64-bit TOD format The TX client must maintain the desired value on this signal while the TX SOP signal is asserted. If you turned on Enable 96b Time of Day Format and the client specifies the 64-bit format, the IP core maps the 64-bit TOD format time-of-day (32 bits of seconds and 32 bits of nanoseconds) as is in bits [79:16] of the 96-bit timestamp and TOD signals. If you turned off Enable 96b Time of Day Format and the client specifies the 96-bit format (V2), the results are undefined.
`tx_etstamp_ins_ctrl_offset_timestamp[15:0]`	Input	Specifies the byte offset of the timestamp information in the current packet if the TX client simultaneously asserts `tx_etstamp_ins_ctrl_timestamp_insert`. The IP core overwrites the value at this offset. The TX client must maintain the desired value on this signal while the TX SOP signal is asserted. If the packet supports V2 format, the timestamp has 96 bits. In this case, the IP core inserts ten bytes (bits [95:16]) of the timestamp at this offset and the remaining two bytes (bits [15:0]) of the timestamp at the offset specified in `tx_etstamp_ins_ctrl_offset_correction_field`. The TX client must ensure that: The offset supports inclusion of the entire timestamp in the packet. If the packet is more than 256 bytes, the offset supports inclusion of the entire timestamp in the first 256 bytes of the packet. The timestamp bytes do not overlap with the bytes in any other field, including the UDP checksum field. (If these particular two fields overlap, the result is undefined).
`tx_etstamp_ins_ctrl_offset_correction_field[15:0]`	Input	If the TX client simultaneously asserts `tx_etstamp_ins_ctrl_residence_time_update`, this signal specifies the byte offset of the correction field in the current packet. If the TX client simultaneously asserts `tx_etstamp_ins_ctrl_timestamp_insert` and deasserts (sets to the value of 0) the `tx_etstamp_ins_ctrl_timestamp_format` signal, this signal specifies the byte offset of bits [15:0]] of the timestamp. The TX client must maintain the desired value on this signal while the TX SOP signal is asserted. In addition, the TX client must ensure that: The offset supports inclusion of the entire correction field or timestamp in the packet. If the packet is more than 256 bytes, the offset supports inclusion of the entire timestamp or correction field in the first 256 bytes of the packet. The correction field or timestamp bytes do not overlap with the bytes in any other field, including the UDP checksum field. (If these particular two fields overlap, the result is undefined).
`tx_etstamp_ins_ctrl_checksum_zero`	Input	The TX client asserts this signal during a TX SOP cycle to tell the IP core to zero the UDP checksum in the current packet. If the TX client asserts the `tx_etstamp_ins_ctrl_checksum_correct` signal, it cannot assert this signal. This signal is meaningful only in one-step clock mode. A zeroed UDP checksum indicates the checksum value is not necessarily correct. This information is useful to tell the application to skip checksum checking of UDP IPv4 packets. This function is illegal for UDP IPv6 packets.
`tx_etstamp_ins_ctrl_offset_checksum_field[15:0]`	Input	Indicates the byte offset of the UDP checksum in the current packet. The TX client must ensure this signal has a valid value during each TX SOP cycle when it also asserts the `tx_etstamp_ins_ctrl_checksum_zero` signal. Holds the byte offset of the two bytes in the packet that the IP core should reset. This signal is meaningful only in one-step clock mode. The TX client must ensure that: The offset supports inclusion of the entire checksum in the packet. The checksum bytes do not overlap with the bytes in any other field, including the timestamp bytes. (If these particular two fields overlap, the result is undefined).
`tx_etstamp_ins_ctrl_checksum_correct`	Input	The TX client asserts this signal during a TX SOP cycle to tell the IP core to update (correct) the UDP checksum in the current packet. If the TX client asserts the `tx_etstamp_ins_ctrl_checksum_zero` signal, it cannot assert this signal. This signal is meaningful only in one-step clock mode. The application must assert this signal for correct processing of UDP IPv6 packets.
`tx_etstamp_ins_ctrl_offset_checksum_correction[15:0]`	Input	Indicates the byte offset of the UDP checksum in the current packet. The TX client must ensure this signal has a valid value during each TX SOP cycle when it also asserts the `tx_etstamp_ins_ctrl_checksum_correct` signal. Holds the byte offset of the two bytes in the packet that the IP core should correct. In a PTP packet, two bytes before the CRC represent the valid byte offset for the checksum correction field. This signal is meaningful only in one-step clock mode. The TX client must ensure that: The offset supports inclusion of the entire checksum in the packet. The checksum bytes do not overlap with the bytes in any other field, including the timestamp bytes. (If these particular two fields overlap, the result is undefined).
`tx_egress_asymmetry_update`	Input	Indicates the IP core should include the value in the `TX_PTP_ASYM_DELAY` register in its correction calculations. The TX client must maintain the desired value on this signal while the TX SOP signal is asserted. This option is useful in one-step correction mode.
TX Signals Related to Two Step Processing
`tx_egress_timestamp_request_valid`	Input	Indicates the current packet on the TX client interface is a 1588 PTP packet, and directs the IP core to process the packet in two-step processing mode. In this mode, the IP core outputs the timestamp of the packet when it exits the IP core, and does not modify the packet timestamp information. The TX client must assert and deassert this signal synchronously with the TX SOP signal for the 1588 PTP packet. If the TX client asserts this signal simultaneously with either of `tx_etstamp_ins_ctrl_timestamp_insert` or `tx_etstamp_ins_ctrl_residence_time_update`, the results are undefined.
`tx_egress_timestamp_96b_data[95:0]`	Output	Provides the V2-format timestamp when a 1588 PTP frame begins transmission on the Ethernet link. Value is valid when the `tx_egress_timestamp_96b_valid` signal is asserted. This signal is meaningful only in two-step clock mode. This signal is available only if you turn on the Enable 96b Time of Day Format parameter.
`tx_egress_timestamp_96b_valid`	Output	Indicates that the `tx_egress_timestamp_96b_data` and `tx_egress_timestamp_96b_fingerprint` signals are valid in the current `clk_txmac` clock cycle. This signal is meaningful only in two-step clock mode. This signal is available only if you turn on the Enable 96b Time of Day Format parameter.
`tx_egress_timestamp_64b_data[63:0]`	Output	Provides the timestamp when a V1-format 1588 PTP frame begins transmission on the Ethernet link. Value is valid when the `tx_egress_timestamp_64b_valid` signal is asserted. This signal is meaningful only in two-step clock mode. This signal is available only if you turn on the Enable 64b Time of Day Format parameter.
`tx_egress_timestamp_64b_valid`	Output	Indicates that the `tx_egress_timestamp_64b_data` and `tx_egress_timestamp_64b_fingerprint` signals are valid in the current `clk_txmac` clock cycle. This signal is meaningful only in two-step clock mode. This signal is available only if you turn on the Enable 64b Time of Day Format parameter.
`tx_egress_timestamp_request_fingerprint[(W–1):0]` where `W` is the value between 1 and 16, inclusive, that you specify for the Timestamp fingerprint width parameter	Input	Fingerprint of the current packet. The TX client must assert and deassert this signal synchronously with the TX SOP signal for the 1588 PTP packet.
`tx_egress_timestamp_96b_fingerprint[(W–1):0]` where `W` is the value between 1 and 16, inclusive, that you specify for the Timestamp fingerprint width parameter	Output	Provides the fingerprint of the V2-format 1588 PTP frame currently beginning transmission on the Ethernet link. Value is valid when the `tx_egress_timestamp_96b_valid` signal is asserted. This signal is available only if you turn on the Enable 96b Time of Day Format parameter.
`tx_egress_timestamp_64b_fingerprint[(W–1):0]` where `W` is the value between 1 and 16, inclusive, that you specify for the Timestamp fingerprint width parameter	Output	Provides the fingerprint of the Intel 64-bit 1588 PTP frame currently beginning transmission on the Ethernet link. Value is valid when the `tx_egress_timestamp_64b_valid` signal is asserted. This signal is available only if you turn on the Enable 64b Time of Day Format parameter.
RX Signals
`rx_ingress_timestamp_96b_data[95:0]`	Output	Whether or not the current packet on the RX client interface is a 1588 PTP packet, indicates the V2-format timestamp when the IP core received the packet on the Ethernet link. The IP core provides a valid value on this signal in the same cycle it asserts the RX SOP signal for 1588 PTP packets. This signal is available only if you turn on the Enable 96b Time of Day Format parameter.
`rx_ingress_timestamp_96b_valid`	Output	Indicates that the `rx_ingress_timestamp_96b_data` signal is valid in the current cycle. This signal is redundant with the RX SOP signal for 1588 PTP packets. This signal is available only if you turn on the Enable 96b Time of Day Format parameter.
`rx_ingress_timestamp_64b_data[63:0]`	Output	Whether or not the current packet on the RX client interface is a 1588 PTP packet, indicates the 64-bit TOD (in Intel 64-bit format) when the IP core received the packet on the Ethernet link. The IP core provides a valid value on this signal in the same cycle it asserts the RX SOP signal for 1588 PTP packets. This signal is available only if you turn on the Enable 64b Time of Day Format parameter.
`rx_ingress_timestamp_64b_valid`	Output	Indicates that the `rx_ingress_timestamp_64b_data` signal is valid in the current cycle. This signal is redundant with the RX SOP signal for 1588 PTP packets. This signal is available only if you turn on the Enable 64b Time of Day Format parameter.

3.2.14. PHY Status Interface

The rx_pcs_ready output signal is available to provide status information to user logic. This signal is asserted when the RX lanes are fully aligned and ready to receive data.

The tx_lanes_stable output signal is available to provide status information to user logic. This signal is asserted when the TX lanes are fully aligned and ready to transmit data.

3.2.15. Transceiver PHY Serial Data Interface

The core uses an <n>-lane digital interface to send data to the TX high-speed serial I/O pins operating at 10.3125 Gbps. The rx_serial and tx_serial ports connect to the 10.3125 Gbps pins. Virtual lanes 0 and 1 transmit data on tx_serial[0].

3.2.16. Low Latency 40GBASE-KR4 IP Core Variations

The LL 40GBASE-KR4 IP core supports low-level control of analog transceiver properties for link training and auto-negotiation in the absence of a predetermined environment for the IP core. For example, an Ethernet IP core in a backplane may have to communicate with different link partners at different times. When it powers up, the environment parameters may be different than when it ran previously. The environment can also change dynamically, necessitating reset and renegotiation of the Ethernet link.

The LL 40GbE IP core 40GBASE-KR4 variations implement the IEEE Backplane Ethernet Standard 802.3ap-2007 . The LL 40GbE IP core provides this reconfiguration functionality in Arria 10 devices by configuring each physical Ethernet lane with an Intel Backplane Ethernet 10GBASE-KR PHY IP core if you turn on Enable KR4 in the LL 40GbE parameter editor. The parameter is available in variations parameterized with these values:

Device family: Arria 10
Protocol speed: 40GbE
Enable 1588 PTP : Off

The IP core includes the option to implement the following features:

KR auto-negotiation provides a process to explore coordination with a link partner on a variety of different common features. The 40GBASE-KR4 variations of the LL 40GbE IP core can auto-negotiate only to a 40GBASE-KR4 configuration. Turn on the Enable KR4 Reconfiguration and Enable Auto-Negotiation parameters to configure support for auto-negotiation.
Link training provides a process for the IP core to train the link to the data frequency of incoming data, while compensating for variations in process, voltage, and temperature. Turn on the Enable KR4 Reconfiguration and Enable Link Training parameters to configure support for link training.
After the link is up and running, forward error correction (FEC) provides an error detection and correction mechanism to enable noisy channels to achieve the Ethernet-mandated bit error rate (BER) of 10^-12. Turn on the Include FEC sublayer parameter to configure support for FEC.

The LL 40GBASE-KR4 IP core variations include separate link training and FEC modules for each of the four Ethernet lanes, and a single auto-negotiation module. You specify the master lane for performing auto-negotiation in the parameter editor, and the IP core also provides register support to modify the selection dynamically.

Intel provides a testbench for LL 40GBASE-KR4 IP core variations with an Avalon-ST client interface that generate their own TX MAC clock (Use external TX MAC PLL is turned off). Intel provides a hardware design example for all LL 40GBASE-KR4 IP core variations that generate their own TX MAC clock, to assist you in integrating your LL 40GBASE-KR4 IP core into your complete design. You can examine the design example for an example of how to drive and connect the 40GBASE-KR4 IP core.

IP core FEC functionality relies on register settings in the LL 40GBASE-KR4 registers and on some specific register fields in the Arria 10 device registers.

To simulate correctly and to run correctly in hardware, you must drive the reconfig_clk and the clk_status inputs from the same source clock.

3.2.17. Control and Status Interface

The control and status interface provides an Avalon-MM interface to the IP core control and status registers. The Avalon-MM interface implements a standard memory-mapped protocol. You can connect an embedded processor or JTAG Avalon master to this bus to access the control and status registers.

Note:

This interface cannot handle multiple pending read transfers. Despite the presence of the status_readdata_valid signal, this Avalon-MM interface is non-pipelined with variable latency.

Table 27. Avalon-MM Control and Status Interface SignalsThe `clk_status` clocks the signals on the LL 40GbE IP core control and status interface. The synchronous `reset_status` reset signal resets the interface.
Signal Name	Direction	Description
`status_addr` `[15:0]`	Input	Address for reads and writes
`status_read`	Input	Read command
`status_write`	Input	Write command
`status_writedata` `[31:0]`	Input	Data to be written
`status_readdata` `[31:0]`	Output	Read data
`status_readdata_valid`	Output	Read data is ready for use
`status_waitrequest`	Output	Busy signal indicating control and status interface cannot currently respond to requests
`status_read_timeout`	Output	Timeout signal indicating read data did not arrive when expected. Hardwired timeout counter is set so that this timeout should only occur in the presence of an error condition, such as `status_addr` with an undefined value. This signal is not an Avalon-MM defined signal

The status interface is designed to operate at a low frequencies, typically 100 MHz, so that control and status logic does not compete for resources with the surrounding high speed datapath.

Figure 34. Read and Write Register Access ExampleThe waveform demonstrates a write-read-write sequence of back-to-back register accesses. The delay from the time the application asserts status_read until the IP core asserts status_readdata_valid and deasserts status_waitrequest is approximately 80 clk_status cycles in this example.

3.2.18. Arria 10 Transceiver Reconfiguration Interface

Arria 10 variations provide a dedicated Avalon-MM interface, called the Arria 10 transceiver reconfiguration interface, to access the transceiver registers. You access the Arria 10 Native PHY IP core registers through this dedicated interface and not through the IP core general purpose control and status interface.

The Avalon-MM interface implements a standard memory-mapped protocol. You can connect an embedded processor or JTAG Avalon master to this bus to access the registers of the embedded Arria 10 Native PHY IP core.

Table 28. Avalon-MM Arria 10 Reconfiguration Interface SignalsThe `reconfig_clk` clocks the signals on the LL 40GbE IP core Arria 10 transceiver reconfiguration interface. The synchronous `reconfig_reset` reset signal resets the interface.
Signal Name	Direction	Description
`reconfig_address` `[11:0]`	Input	Address for reads and writes
`reconfig_read`	Input	Read command
`reconfig_write`	Input	Write command
`reconfig_writedata` `[31:0]`	Input	Data to be written
`reconfig_readdata` `[31:0]`	Output	Read data
`reconfig_waitrequest`	Output	Interface busy signal

The Arria 10 reconfiguration interface is designed to operate at a low frequency, 100 MHz to 125 MHz, so that the user's Arria 10 transceiver reconfiguration logic does not compete for resources with the surrounding high speed datapath.

3.2.19. Clocks

You must set the transceiver reference clock (clk_ref) frequency to a value that the IP core supports. The LL 40GbE IP core supports clk_ref frequencies of 644.53125 MHz ±100 ppm and 322.265625 MHz ± 100 ppm. The ±100ppm value is required for any clock source providing the transceiver reference clock.

Sync–E IP core variations are IP core variations for which you turn on Enable SyncE in the parameter editor. These variations provide the RX recovered clock as a top-level output signal. This option is available only for IP core variations that target an Arria 10 device.

The Synchronous Ethernet standard, described in the ITU-T G.8261, G.8262, and G.8264 recommendations, requires that the TX clock be filtered to maintain synchronization with the RX reference clock through a sequence of nodes. The expected usage is that user logic drives the TX PLL reference clock with a filtered version of the RX recovered clock signal, to ensure the receive and transmit functions remain synchronized. In this usage model, a design component outside the LL 40GbE IP core performs the filtering.

Table 29. Clock InputsDescribes the input clocks that you must provide.
Signal Name	Description
`clk_status`	Clocks the control and status interface. The clock quality and pin chosen are not critical. `clk_status` is expected to be a 100–125 MHz clock. In LL 40GBASE-KR4 variations, you must drive `clk_status` and `reconfig_status` from a single clock source.
`reconfig_clk`	Clocks the Arria 10 transceiver reconfiguration interface. The clock quality and pin chosen are not critical. `reconfig_clk` is expected to be a 100 MHz clock; the allowed frequency range depends on Arria 10 transceiver requirements and is not IP core specific. In LL 40GBASE-KR4 variations, you must drive `clk_status` and `reconfig_clk` from a single clock source.
`clk_ref`	In IP core variations that target an Arria 10 device, `clk_ref` is the reference clock for the transceiver RX CDR PLL. In other IP core variations, `clk_ref` is the reference clock for the transceiver TX PLL and the RX CDR PLL. The frequency of this input clock must match the value you specify for PHY reference frequency in the IP core parameter editor, with a ±100 ppm accuracy per the IEEE 802.3ba-2010 High Speed Ethernet Standard.. In addition, `clk_ref` must meet the jitter specification of the IEEE 802.3ba-2010 High Speed Ethernet Standard. The PLL and clock generation logic use this reference clock to derive the transceiver and PCS clocks. The input clock should be a high quality signal on the appropriate dedicated clock pin. Refer to the relevant device datasheet for transceiver reference clock phase noise specifications.
`clk_txmac_in`	If you turn on Use external TX MAC PLL in the LL 40GbE parameter editor, this clock drives the TX MAC. The port is expected to receive the clock from the external TX MAC PLL and drives the internal clock `clk_txmac`. The required TX MAC clock frequency is 312.5 MHz . User logic must drive `clk_txmac_in` from a PLL whose input is the PHY reference clock, `clk_ref`.
`tx_serial_clk[3:0]`	These input clocks are present only in variations that target an Arria 10 device. They are part of the external PLL interface to these variations. Each clock targets a single transceiver PHY link. You must drive these clocks from one or more TX transceiver PLLs that you configure separately from the LL 40GbE IP core.

Table 30. Clock OutputsDescribes the output clocks that the IP core provides. In most cases these clocks participate in internal clocking of the IP core as well.
Signal Name	Description
`clk_txmac`	The TX clock for the IP core is `clk_txmac`. The TX MAC clock frequency is 312.5 MHz . If you turn on Use external TX MAC PLL in the LL 40GbE parameter editor, the `clk_txmac_in` input clock drives `clk_txmac`.
`clk_rxmac`	The RX clock for the IP core is `clk_rxmac`. The RX MAC clock frequency is 312.5 MHz . This clock is only reliable when `rx_pcs_ready` has the value of 1. The IP core generates `clk_rxmac` from a recovered clock that relies on the presence of incoming RX data.
`clk_rx_recover`	RX recovered clock. This clock is available only if you turn on Enable SyncE in the LL 40GbE parameter editor. The RX recovered clock frequency is 257.8125 MHz . The expected usage is that you drive the TX transceiver PLL reference clock with a filtered version of `clk_rx_recover`, to ensure the receive and transmit functions remain synchronized in your Synchronous Ethernet system. To do so you must instantiate an additional component in your design. The IP core does not provide filtering.

Figure 35. Clock Generation Circuitry Provides a high-level view of the clock generation circuitry and clock distribution to the transceiver. In Arria 10 variations, the TX transceiver PLL is configured outside the LL 40GbE IP core, and clk_ref drives the RX CDR PLL. In Arria 10 variations, you can connect a separate reference clock for the external TX transceiver PLL.

3.2.20. Resets

The LL 40GbE IP core has a single asynchronous reset signal. Asserting this signal resets the full IP core. You must hold the reset signal asserted for ten clk_status clock cycles to ensure proper hold time.

You should not release the reset signal until after you observe that the reference clock is stable. If the reference clock is generated from an fPLL, wait until after the fPLL locks. Ten clk_status cycles should be sufficient for the fPLL to lock and the reference clock to stabilize.

Table 31. Asynchronous Reset Signal
Signal Name	Direction	Description
`reset_async`	Input	LL 40GbE IP core asynchronous reset signal

In addition, the LL 40GbE IP core has one or two of the following synchronous reset signals:

reset_status—Resets the IP core control and status interface, an Avalon-MM interface. Associated clock is the clk_status clock, which clocks the control and status interface.
reconfig_reset—Resets the IP core Arria 10 transceiver reconfiguration interface, an Avalon-MM interface. Associated clock is the reconfig_clk, which clocks the Arria 10 transceiver reconfiguration interface. This signal is available only in Arria 10 IP core variations.

3.3. Signals

This section lists the external signals of the different LL 40GbE IP core variations.

3.3.1. LL 40GbE IP Core Signals

The signals of the LL 40GbE IP core are described in the following formats:

The figure identifies the IP core interfaces.
Tables list the signals and the interfaces to which they belong.
Links guide you to descriptions for the individual signals, by interface. The links appear in Related Links.

Figure 36. Top-Level Signals of the LL 40GbE IP Core In the figure, <N> is the number of priority flow control queues. (<N> = 1 for IP cores configured with standard flow control or with no flow control, and <N> = the value of the relevant parameter for IP cores configured with priority-based flow control). In the 1588 PTP signals, <W> is the width of the fingerprint.

Table 32. LL 40GbE IP Core Signals
Signal Name	Direction	Interface
`clk_ref`	Input	Clocks
`clk_rx_recover`	Output	Clocks This signal is only available if you turn on Enable SyncE in the parameter editor.
`reset_async`	Input	Reset
`tx_serial[3:0]`	Output	Transceiver PHY serial data interface
`rx_pcs_ready`	Output	PHY status
`tx_lanes_stable`	Output	PHY status
`clk_txmac_in`	Input	Clocks Interface to external TX MAC PLL This signal is only available if you turn on Enable external TX MAC PLL in the parameter editor.
`clk_txmac`	Output	Clocks TX client interface
`l4_tx_data[255:0]`	Input	Avalon-ST TX client interface Each IP core instance has Avalon-ST TX and RX client interfaces, or custom streaming TX and RX client interfaces.
`l4_tx_empty[4:0]`	Input
`l4_tx_startofpacket`	Input
`l4_tx_endofpacket`	Input
`l4_tx_ready`	Output
`l4_tx_valid`	Input
`l4_tx_error`	Input
`din[127:0]`	Input	Custom streaming TX client interface Each IP core instance has Avalon-ST TX and RX client interfaces, or custom streaming TX and RX client interfaces.
`din_sop[1:0]`	Input
`din_eop[1:0]`	Input
`din_eop_empty[5:0]`	Input
`din_idle[1:0]`	Input
`din_req`	Output
`tx_error[1:0]`	Input
`clk_rxmac`	Output	Clocks RX client interface
`l4_rx_data[255:0]`	Output	Avalon-ST RX client interface Each IP core instance has Avalon-ST TX and RX client interfaces, or custom streaming TX and RX client interfaces.
`l4_rx_empty[4:0]`	Output
`l4_rx_startofpacket`	Output
`l4_rx_endofpacket`	Output
`l4_rx_error[5:0]`	Output
`l4_rx_valid`	Output
`l4_rx_fcs_valid`	Output
`l4_rx_fcs_error`	Output
`l4_rx_status[2:0]`	Output
`dout_d[127:0]`	Output	Custom streaming RX client interface Each IP core instance has Avalon-ST TX and RX client interfaces, or custom streaming TX and RX client interfaces.
`dout_c[15:0]`	Output
`dout_sop[1:0]`	Output
`dout_eop[1:0]`	Output
`dout_eop_empty[5:0]`	Output
`dout_idle[1:0]`	Output
`rx_error[5:0]`	Output
`rx_fcs_error`	Output
`rx_fcs_valid`	Output
`rx_status[2:0]`	Output
`dout_valid`	Output
`pause_insert_tx[<N>-1:0]`	Input	Pause control and generation interface
`pause_receive_rx[<N>-1:0]`	Output	Pause control and generation interface
`remote_fault_status`	Output	Link fault signaling interface These signals are available only in IP core variations that include the link fault signaling module.
`local_fault_status`	Output
`unidirectional_en`	Output	Link fault signaling interface, Clause 66 status These signals are available only in IP core variations that include the link fault signaling module.
`link_fault_gen_en`	Output
`tx_inc_64`	Output	TX statistics counter increment vectors These signals are available whether or not your IP core includes TX statistics counters.
`tx_inc_127`	Output
`tx_inc_255`	Output
`tx_inc_511`	Output
`tx_inc_1023`	Output
`tx_inc_1518`	Output
`tx_inc_max`	Output
`tx_inc_over`	Output
`tx_inc_mcast_data_err`	Output
`tx_inc_mcast_data_ok`	Output
`tx_inc_bcast_data_err`	Output
`tx_inc_bcast_data_ok`	Output
`tx_inc_ucast_data_err`	Output
`tx_inc_ucast_data_ok`	Output
`tx_inc_mcast_ctrl`	Output
`tx_inc_bcast_ctrl`	Output
`tx_inc_ucast_ctrl`	Output
`tx_inc_pause`	Output
`tx_inc_fcs_err`	Output
`tx_inc_fragment`	Output
`tx_inc_jabber`	Output
`tx_inc_sizeok_fcserr`	Output
`rx_inc_runt`	Output	RX statistics counter increment vectors These signals are available whether or not your IP core includes RX statistics counters.
`rx_inc_64`	Output
`rx_inc_127`	Output
`rx_inc_255`	Output
`rx_inc_511`	Output
`rx_inc_1023`	Output
`rx_inc_1518`	Output
`rx_inc_max`	Output
`rx_inc_over`	Output
`rx_inc_mcast_data_err`	Output
`rx_inc_mcast_data_ok`	Output
`rx_inc_bcast_data_err`	Output
`rx_inc_bcast_data_ok`	Output
`rx_inc_ucast_data_err`	Output
`rx_inc_ucast_data_ok`	Output
`rx_inc_mcast_ctrl`	Output
`rx_inc_bcast_ctrl`	Output
`rx_inc_ucast_ctrl`	Output
`rx_inc_pause`	Output
`rx_inc_fcs_err`	Output
`rx_inc_fragment`	Output
`rx_inc_jabber`	Output
`rx_inc_sizeok_fcserr`	Output
`rx_inc_pause_ctrl_err`	Output
`rx_inc_mcast_ctrl_err`	Output
`rx_inc_bcast_ctrl_err`	Output
`rx_inc_ucast_ctrl_err`	Output
`tx_inc_octetsOK[15:0]`	Output	OctetOK Count interface
`tx_inc_octetsOK_valid`	Output
`rx_inc_octetsOK[15:0]`	Output
`rx_inc_octetsOK_valid`	Output
`clk_status`	Input	Clocks Control and status interface
`reset_status`	Input	Resets Control and status interface
`status_addr[15:0]`	Input	Control and status interface
`status_read`	Input
`status_write`	Input
`status_writedata[31:0]`	Input
`status_readdata[31:0]`	Output
`status_readdata_valid`	Output
`status_waitrequest`	Output
`status_read_timeout`	Output
`tx_time_of_day_96b_data[95:0]`	Input	1588 PTP interface These signals are available only if 1588 PTP functionality is included in the IP core.
`tx_time_of_day_64b_data[63:0]`	Input
`rx_time_of_day_96b_data[95:0]`	Input
`rx_time_of_day_64b_data[63:0]`	Input
`tx_etstamp_ins_ctrl_timestamp_insert`	Input
`tx_etstamp_ins_ctrl_residence_time_update`	Input
`tx_etstamp_ins_ctrl_ingress_timestamp_96b[95:0]`	Input
`tx_etstamp_ins_ctrl_ingress_timestamp_64b[63:0]`	Input
`tx_etstamp_ins_ctrl_timestamp_format`	Input
`tx_etstamp_ins_ctrl_residence_time_calc_format`	Input
`tx_etstamp_ins_ctrl_offset_timestamp[15:0]`	Input
`tx_etstamp_ins_ctrl_offset_correction_field[15:0]`	Input
`tx_etstamp_ins_ctrl_checksum_zero`	Input
`tx_etstamp_ins_ctrl_offset_checksum_field[15:0]`	Input
`tx_etstamp_ins_ctrl_checksum_correct`	Input
`tx_etstamp_ins_ctrl_offset_checksum_correction[15:0]`	Input
`tx_egress_asymmetry_update`	Input
`tx_egress_timestamp_request_valid`	Input
`tx_egress_timestamp_96b_data[95:0]`	Output
`tx_egress_timestamp_96b_valid`	Output
`tx_egress_timestamp_64b_data[63:0]`	Output
`tx_egress_timestamp_64b_valid`	Output
`tx_egress_timestamp_request_fingerprint[(W–1):0]`	Input
`tx_egress_timestamp_96b_fingerprint[(W–1):0]`	Output
`tx_egress_timestamp_64b_fingerprint[(W–1):0]`	Output
`rx_ingress_timestamp_96b_data[95:0]`	Output
`rx_ingress_timestamp_96b_valid`	Output
`rx_ingress_timestamp_64b_data[63:0]`	Output
`rx_ingress_timestamp_64b_valid`	Output
`reconfig_to_xcvr[559:0]`	Input	Interface to Stratix V reconfiguration controller These signals are available in Stratix V devices only.
`reconfig_from_xcvr[367:0]`	Output
`reconfig_busy`	Input
`reconfig_clk`	Input	Clocks Arria 10 Native PHY IP core reconfiguration interface This signal is available in Arria 10 devices only.
`reconfig_reset`	Input	Resets Arria 10 Native PHY IP core reconfiguration interface This signal is available in Arria 10 devices only.
`reconfig_address` `[11:0]`	Input	Arria 10 Native PHY IP core reconfiguration interface These signals are available in Arria 10 devices only.
`reconfig_read`	Input
`reconfig_write`	Input
`reconfig_writedata[31:0]`	Input
`reconfig_readdata[31:0]`	Output
`reconfig_waitrequest`	Output
`pll_locked`	Input	External transceiver PLL interface. These signals are available in Arria 10 devices only.
`tx_serial_clk[3:0]`	Input

3.4. Software Interface: Registers

This section provides information about the memory-mapped registers. You access these registers using the IP core control and status interface. The registers use 32-bit addresses; they are not byte addressable.

Write operations to a read-only register field have no effect. Read operations that address a Reserved register return an unspecified constant. Write operations to Reserved registers have no effect. Accesses to registers that do not exist in your IP core variation have an unspecified result.

Table 33. LL 40GbE IP Core Register Map OverviewLists the main ranges of the memory mapped registers for the LL 40GbE IP core. Addresses are word addresses. Register address range 0x100–0x2FF is Reserved.
Word Offset	Register Category
0x0B0–0x0FF	40GBASE-KR4 registers
0x300–0x3FF	PHY registers
0x400–0x4FF	TX MAC registers
0x500–0x5FF	RX MAC registers
0x600–0x6FF	TX flow control (pause functionality) registers
0x700–0x7FF	RX flow control (pause functionality) registers
0x800–0x8FF	TX statistics counters
0x900–0x9FF	RX statistics counters
0xA00–0xAFF	TX 1588 PTP registers
0xB00–0xBFF	RX 1588 PTP registers

Table 34. IP Core Address Map Lists the memory mapped registers for the LL 40GbE IP core. Each register is 32 bits, and the addresses (word offsets) each address a full word. This table does not list the Revision ID, scratch, and name registers present in each of the address ranges at offsets 0x00, 0x01, and 0x02–0x04 respectively. However, those registers appear in the detailed listings with descriptions.
Word Offset	Register Description
0x0B0–0x0BD	40GBASE-KR4 top-level and FEC registers Accessible only if you turn on Enable KR. FEC registers are accessible only if you also turn on Include FEC sublayer.
0x0BE–0x0BF	Reserved.
0x0C0–0x0CC	40GBASE-KR4 auto-negotiation registers Accessible only if you turn on Enable KR and Enable Auto-Negotiation.
0x0CD–0x0CF	Reserved.
0x0D0–0x0EB	40GBASE-KR4 link training registers Accessible only if you turn on Enable KR and Enable Link Training.
0x0EC–0x0FF	Reserved.
0x310–0x344	PHY registers available in all IP core variations
0x405	Link fault signaling register `LINK_FAULT_CONFIG` Accessible only if you turn on Enable link fault generation
0x406	IPG column removal register `IPG_COL_REM` Accessible only if you turn on Average interpacket gap
0x407	TX maximum size Ethernet frame (in bytes) `MAX_TX_SIZE_CONFIG`. Value determines whether the IP core increments the `CNTR_TX_OVERSIZE` register
0x506	RX maximum size Ethernet frame (in bytes) `MAX_RX_SIZE_CONFIG`. Value determines whether the IP core increments the `CNTR_RX_OVERSIZE` register.
0x507	RX CRC forwarding configuration register `MAC_CRC_CONFIG`
0x508	Link fault status register Provides link fault status information if you turn on Enable link fault generation . Returns zeroes if you turn off Enable link fault generation .
0x50A	Enable RX payload length checking register Provides enable bit to determine whether the RX error signal flags payload lengths that do not match the length field..
0x605–0x60A	Transmit side pause registers Accessible only if you set Flow control mode to the value Standard flow control or Priority-based flow control.
0x700–0x703	Receive side pause registers Accessible only if you set Flow control mode to the value Standard flow control or Priority-based flow control.
0x800–0x837, 0x860–0x861	Transmit side statistics registers Accessible only if you turn on Enable TX statistics
0x845	Transmit statistics counters configuration register `CNTR_TX_CONFIG` Accessible only if you turn on Enable TX statistics
0x846	Transmit statistics counters status register Accessible only if you turn on Enable TX statistics
0x900–0x937, 0x960–0x961	Receive side statistics registers Accessible only if you turn on Enable RX statistics
0x945	Receive statistics counters configuration register `CNTR_RX_CONFIG` Accessible only if you turn on Enable RX statistics
0x946	Receive statistics counters status register Accessible only if you turn on Enable RX statistics
0xA00–0xA0C	TX 1588 PTP registers Accessible only if you turn on Enable 1588 PTP
0xB00–0xB06	RX 1588 PTP registers Accessible only if you turn on Enable 1588 PTP

Table 35. LL 40GbE Hardware Design Example RegistersLists the memory mapped register ranges for the LL 40GbE IP core hardware design example
Word Offset	Register Category
0x1000–0x1016	Packet client registers
0x2004–0x2023	Reserved
0x4000–0x4C00	Arria 10 dynamic reconfiguration register base addresses for four-lane variations. Register base address is 0x4000 for Lane 0, 0x4400 for Lane 1, 0x4800 for Lane 2, and 0x4C00 for Lane 3. (Bits [11:10] specify the lane).

3.4.1. LL 40GbE IP Core Registers

The following sections describe the registers included in the LL 40GbE IP core.

3.4.1.1. PHY Registers

Table 36. PHY Registers
Addr	Name	Bit	Description	HW Reset Value	Access
0x300	`PHY_REVID`	[31:0]	IP core PHY module revision ID.	0x02062015	RO
0x301	`PHY_SCRATCH`	[31:0]	Scratch register available for testing.	32'b0	RW
0x302	`PHY_NAME_0`	[31:0]	First 4 characters of IP core variation identifier string " 40GE pcs " .		RO
0x303	`PHY_NAME_1`	[31:0]	Next 4 characters of IP core variation identifier string " 40GE pcs " .		RO
0x304	`PHY_NAME_2`	[31:0]	Final 4 characters of IP core variation identifier string " 40GE pcs " .		RO
0x310	`PHY_CONFIG`	[5]	set_data_lock: Directs the PLL to lock to data.	6'b0	RW
		[4]	set_ref_lock: Directs the PLL to lock to the reference clock.
		[3]	rxp_ignore_freq: Directs the IP core to proceed with the internal reset sequence (to reset the RX PLL) without waiting for the RX CDR PLL to lock.
		[2]	soft_rxp_rst: RX PLL soft reset
		[1]	soft_txp_rst: TX PLL soft reset
		[0]	eio_sys_rst: PMA system reset. Set this bit to start the internal reset sequence.
0x313	`PHY_PMA_SLOOP`	[3:0] or [9:0]	Serial PMA loopback. Each bit that is asserted directs the IP core to connect the corresponding TX–RX lane pair on the internal loopback path, by setting the corresponding transceiver in serial loopback mode.	0	RW
0x314	`PHY_PCS_INDIRECT_ADDR`	[2:0]	Supports indirect addressing of individual FIFO flags in the 10G PCS Native PHY IP core. Program this register with the encoding for a specific FIFO flag. The flag values (one per transceiver) are then accessible in the `PHY_PCS_INDIRECT_DATA` register. The value in the `PHY_PCS_INDIRECT_ADDR` register directs the IP core to make available the following FIFO flag: 3'b111: RX partial empty 3'b110: RX partial full 3'b101: RX empty 3'b100: RX full 3'b011: TX partial empty 3'b010: TX partial full 3'b001: TX empty 3'b000: TX full	3'b0	RW
0x315	`PHY_PCS_INDIRECT_DATA`	[3:0] or [9:0]	PCS indirect data. To read a FIFO flag, set the value in the `PHY_PCS_INDIRECT_ADDR` register to indicate the flag you want to read. After you set the specific flag indication in the `PHY_PCS_INDIRECT_ADDR` register, each bit [n] in the `PHY_PCS_INDIRECT_DATA` register has the value of that FIFO flag for the transceiver channel for lane [n]. This register has four valid bits [3:0].	TX full flags	RO
0x320	`PHY_TX_PLL_LOCKED`	[9:0]	Each bit that is asserted indicates that the corresponding lane TX transceiver PLL is locked.	10'b0	RO
0x321	`PHY_EIOFREQ_LOCKED`	[9:0]	Each bit that is asserted indicates that the corresponding lane RX CDR PLL is locked.	10'b0	RO RO
0x322	`PHY_TX_COREPLL_LOCKED`	[2]	RX PLL is locked.	3'b0	RO
		[1]	TX MAC PLL is locked.
		[0]	TX PCS is ready.
0x323	`PHY_FRAME_ERROR`	[3:0] or [19:0]	Each bit that is asserted indicates that the corresponding virtual lane has a frame error. If you read a non-zero value in this register, the virtual lanes that correspond to non-zero bits have observed frame errors. You can clear these bits with the `PHY_SCLR_FRAME_ERROR` register. Intel recommends that you set bit [0] of the `PHY_SCLR_FRAME_ERROR` register and read the `PHY_FRAME_ERROR` register again to determine if the PHY frame error is generated continuously. These bits are not sticky: the IP core clears them more than once while attempting to achieve alignment.	0xF or 0xFFFFF	RO
0x324	`PHY_SCLR_FRAME_ERROR`	[0]	Synchronous clear for `PHY_FRAME_ERROR` register. Write the value of 1 to this register to clear the `PHY_FRAME_ERROR` register. This bit is not self-clearing. You should reset this register to the value of 0 within ten `clk_status` clock cycles. If you do not reset the `PHY_SCLR_FRAME_ERROR` register, the vaue in the `PHY_FRAME_ERROR` register is not useful.	1'b0	RW
0x325	`PHY_EIO_SFTRESET`	[1]	Set this bit to clear the RX FIFO. This bit is not self-clearing.	2'b00	RW
0x325	`PHY_EIO_SFTRESET`	[0]	RX PCS reset: set this bit to reset the RX PCS. This bit is not self-clearing.	2'b00	RW
0x326	`PHY_RXPCS_STATUS`	[1:0]	Indicates the RX PCS is fully aligned and ready to accept traffic. Bit [1]: HI BER status (bit error rate is high according to Ethernet standard definition). This bit maintains the value of 1'b0 unless you turn on Enable link fault generation . Bit [0]: RX PCS fully aligned status.	0	RO
0x340	`PHY_REFCLK_KHZ`	[31:0]	Reference clock frequency in KHz, assuming the `clk_status` clock has the frequency of 100 MHz. The reference clock frequency is the value in the `PHY_REFCLK_KHZ` register times the frequency of the `clk_status` clock, divided by 100.		RO
0x341	`PHY_RXCLK_KHZ`	[31:0]	RX clock (`clk_rxmac`) frequency in KHz, assuming the `clk_status` clock has the frequency of 100 MHz. The RX clock frequency is the value in the `PHY_RXCLK_KHZ` register times the frequency of the `clk_status` clock, divided by 100.		RO
0x342	`PHY_TXCLK_KHZ`	[31:0]	TX clock (`clk_txmac`) frequency in KHz, assuming the `clk_status` clock has the frequency of 100 MHz. The TX clock frequency is the value in the `PHY_TXCLK_KHZ` register times the frequency of the `clk_status` clock, divided by 100.		RO
0x343	`PHY_RECCLK_KHZ`	[31:0]	RX recovered clock frequency in KHz, assuming the `clk_status` clock has the frequency of 100 MHz. The RX recovered clock frequency is the value in the `PHY_RECCLK_KHZ` register times the frequency of the `clk_status` clock, divided by 100.		RO
0x344	`PHY_TXIOCLK_KHZ`	[31:0]	TX PMA clock frequency in KHz, assuming the `clk_status` clock has the frequency of 100 MHz. The TX PMA clock frequency is the value in the `PHY_TX10CLK_KHZ` register times the frequency of the `clk_status` clock, divided by 100.		RO

3.4.1.2. Link Fault Signaling Registers

Table 37. LINK_FAULT_CONFIG Register—Offset 0x405
Name	Bit	Description	Reset Value	Access
Unidir Enable	[1]	When asserted, the IP core includes Clause 66 support for remote link fault reporting on the Ethernet link.	1'b0	RW
Link Fault Reporting Enable	[0]	1'b1: The PCS generates a proper fault sequence on the Ethernet link, if conditions are met. 1'b0: The PCS does not generate any fault sequences. Whether this bit has the value of 0 or 1, the RX PCS always reports real-time link status on the `local_fault_status` and `remote_fault_status` output signals and in the `Local Fault Status` register at offset 0x508.	1’b1	RW

Table 38. Link Fault Status Register—Offset 0x508
Name	Bit	Description	HW Reset Value	Access
`Remote Fault Status`	[1]	The remote fault status register.The IP core sets this bit when it detects real-time remote faults in the RX MAC. The IP core sets this bit regardless of the settings in the `LINK_FAULT_CONFIG` register.	1'b0	RO
`Local Fault Status`	[0]	The local fault status register. The IP core sets this bit when it detects real-time local faults in the RX MAC. The IP core sets this bit regardless of the settings in the `LINK_FAULT_CONFIG` register.	1'b1	RO

3.4.1.3. LL 40GBASE-KR4 Registers

Most LL 40GBASE-KR4 registers are 10GBASE-KR PHY registers of the Arria 10 10GBASE-KR PHY IP core, documented in the Arria 10 Transceiver PHY User Guide. Exceptions are:

The register offsets of the 10GBASE-KR PHY registers are offset by negative 0x400 in the LL 40GBASE-KR4 variations of the LL 40GbE IP core. The Arria 10 10GBASE-KR PHY IP core registers begin at offset 0x4B0. In the LL 40GBASE-KR4 IP core, these registers begin at offset 0x0B0.
The LL 40GBASE-KR4 variations of the LL 40GbE IP core have additional 40GBASE-KR4 related registers and register fields.
The FEC error insertion feature requires that you program some Arria 10 device registers through the Arria 10 dynamic reconfiguration interface. The FEC error count is collected in other Arria 10 device registers that you access through the Arria 10 dynamic reconfiguration interface. You access the relevant Arria 10 device registers at offsets 0xBD through 0xE3 for Lane 0, 0x4BD through 0x4E3 for Lane 1, 0x8BD through 0x8E3 for Lane 2, and 0xCBD through 0xCE3 for Lane 3. The descriptions of the LL 40GBASE-KR4 registers that depend on these Arria 10 device registers provide the individual A10 register information.

For your convenience, the LL 40GbE IP core user guide includes an appendix with the 10GBASE-KR PHY register descriptions: Arria 10 10GBASE-KR Registers .

Table 39. LL 40GbE IP Core 40GBASE-KR4 Registers and Register Fields Not in Arria 10 10GBASE-KR PHY IP Core
Documents the differences between the Arria 10 10GBASE-KR PHY register definitions and the 40GBASE-KR4 registers of the LL 40GbE IP core. All 10GBASE-KR PHY registers and register fields not listed in the table are available in the 40GBASE-KR4 variations of the LL 40GbE IP core.

The 10GBASE-KR PHY register listings are available in the Arria 10 10GBASE-KR Registers appendix and in the *10GBASE-KR PHY Register Definitions* section of the *10GBASE-KR PHY IP Core* section in the *Arria 10 Transceiver PHY User Guide*. The information in these two sources should be identical. Refer to Arria 10 10GBASE-KR Registers for details.

Where the 10GBASE-KR PHY register definitions list 10GBASE-R, substitute 40GBASE-KR4 with auto-negotiation and link training both turned off, and where the 10GBASE-KR PHY register definitions list 10GBASE-KR (except in the description of 0xCB[24:0]), substitute 40GBASE-KR4. Where a register field description in the 10GBASE-KR PHY register definitions refers to link training or FEC in the single-lane 10GBASE-KR PHY IP core, substitute link training or FEC on Lane 0 of the 40GBASE-KR4 IP core variation.

Registers and register bits not described in either location should be considered Reserved.

To modify a field value in any LL 40GBASE-KR4 specific register, whether an underlying 10GBASE-KR PHY IP core register or one of the registers defined in this table, you must perform a read-modify-write operation to ensure you do not modify the values of any other fields in the register.
Address	Name	Bit	Description	HW Reset Value	Access
0x0B0	SEQ Force Mode[3:0]	[7:4]	Forces the sequencer to a specific protocol. Must write the `Reset SEQ` bit (bit [0]) to 1 for the Force to take effect. The following encodings are defined: 0000: No force 0001: GigE mode (unsupported) 0010: XAUI mode (unsupported) 0100: 40GBASE-R4 mode (without auto-negotiation and without link training) 0101: 40GBASE-KR4 mode 1100: 40GBASE-R4 mode with FEC (without auto-negotiation and without link training)	4'b0	RW
	`Enable Arria 10 Calibration`	[8]	When set to 1, it enables the Arria 10 HSSI reconfiguration calibration as part of the PCS dynamic reconfiguration. 0 skips the calibration when the PCS is reconfigured.	1'b1	RW
	`LT Failure Response`	[12]	When set to 1, LT failure causes the PHY to go into data mode. When set to 0, LT failure restarts auto-negotiation (if enabled). If auto-negotiation is not enabled, the PHY will restart LT.	1'b1 in simulation; 1'b0 in hardware	RW
	Reserved	[17]	Reserved Access FEC error indication selection using the Arria 10 dynamic reconfiguration interface. Refer to the descriptions of register 0xB2.
	Reserved	[19]	Reserved
0x0B1	SEQ Reconfig Mode[5:0]	[13:8]	Specifies the Sequencer mode for PCS reconfiguration. The following modes are defined: Bit 8, mode[0]: AN mode Bit 9, mode[1]: LT Mode Bit 10, mode[2]: 40G data mode Bit 11, mode[3]: GigE data mode Bit 12, mode[4]: Reserved for XAUI Bit13, mode[5]: 40G FEC mode
0x0B1	`FEC Block Lock`	[23:20]	FEC Block Lock for lanes [3:0]: bit [20] is FEC block lock for lane 0, bit [21] is FEC block lock for lane 1, bit [22] is FEC block lock for lane 2, and bit [23] is FEC block lock for lane 3.	4'b0	RO
0xB2	KR FEC TX Error Insert, Lane 0	11	Writing a 1 inserts one error pulse into the TX FEC for lane 0, depending on the Transcoder and Burst error settings for lane 0. You must select these settings through the Arria 10 dynamic reconfiguration interface to the Arria 10 device registers before you write a 1 to the KR FEC TX Error Insert, Lane 0 bit. To select these settings for Lane 0, perform a read-modify-write operation sequence at register offset 0xBD. You select a Transcoder error by setting the `transcode_err` bit, resetting the `burst_err` bit, resetting the `burst_err_len` field, and leaving the remaining bits at their previous values. You select a Burst error by setting the `burst_err` bit, specifying the burst error length in the `burst_err_len` field, resetting the `transcode_err` bit, and leaving the remaining bits at their previous values.	1'b0	RWSC
	RCLR_ERRBLK_CNT, Lane 0	12	Writing a 1 resets the error block counters.Writing a 0 causes counting to resume. Each lane has a 32-bit corrected error block counter and a 32-bit uncorrected error block counter in the Arria 10 device registers. Refer to Clause 74.8.4.1 and Clause 74.8.4.2 of IEEE Std 802.3ap-2007. For Lane 0, the corrected error block counter is in the Arria 10 device registers you access through the Arria 10 dynamic reconfiguration interface at offsets 0xDC to 0xDF: `blkcnt_corr[31:0]` is in {0xDF[7:0],0xDE[7:0],0xDD[7:0],0xDC[7:0]}. For Lane 0, the uncorrected error block counter is in the Arria 10 device registers you access through the Arria 10 dynamic reconfiguration interface at offsets 0xE0 to 0xE3: `blkcnt_uncorr[31:0]` is in {0xE3[7:0],0xE2[7:0],0xE1[7:0],0xE0[7:0]}.		RW
	Reserved	[31:13]	Reserved
0x0B5	Register 0xB2 refers to Lane 0. This register is the equivalent of register 0xB2 for Lane 1. The relevant FEC error Arria 10 device registers for Lane 1 are at 0x4BD through 0x4E3 (additional offset of 0x400).				RW
0x0B8	This register is the equivalent of register 0xB2 for Lane 2. The relevant FEC error Arria 10 device registers for Lane 2 are at 0x8BD through 0x8E3 (additional offset of 0x800 compared to the Lane 0 device registers).				RW
0x0BB	This register is the equivalent of register 0xB2 for Lane 3. The relevant FEC error Arria 10 device registers for Lane 3 are at 0xCBD through 0xCE3 (additional offset of 0xC00 compared to the Lane 0 device registers).				RW
0x0C0	`Override AN Channel Enable`	[6]	Overrides the auto-negotiation master channel that you set with the Auto-Negotiation Master parameter, setting the new master channel according to the value in register 0xCC[3:0]. While 0x0C0[6] has the value of 1, the channel encoded in 0xCC[3:0] is the master channel. While 0xC0[6] has the value of 0, the master channel is the channel that you set with the Auto-Negotiation Master parameter.	1'b0	RW
0x0C2	KR4 AN Link Ready [5:0]	[17:12]	Provides a one-hot encoding of an_receive_idle = true and link status for the supported link as described in Clause 73.10.1. The following encodings are defined: 6'b000000: 1000BASE-KX 6'b000001: 10GBASE-KX4 6'b000100: 10GBASE-KR 6'b001000: 40GBASE-KR4 6'b010000: 40GBASE-CR4 6'b100000: 100GBASE-CR10 The only valid value for the LL 40GBASE-KR4 IP core is 6'b001000: 40GBASE-KR4.	6'b001000	RO
0x0CB	`AN LP ADV Tech_A[24:0]`	[24:0]	Received technology ability field bits of Clause 73 Auto Negotiation. The following protocols are defined: A0 1000BASE-KX A1 10GBASE-KX4 A2 10GBASE-KR A3 40GBASE-KR4 A4 40GBASE-CR4 A5 100GBASE-CR10 A24:6 are reserved The only valid value for the LL 40GBASE-KR4 IP core is A3: 40GBASE-KR4. For more information, refer to Clause 73.6.4 and AN LP base page ability registers (7.19-7.21) of Clause 45 of IEEE 802.3ap-2007.	25'b0	RO
0x0CC	`Override AN Channel Select`	[3:0]	If you set the value of the Override AN Channel Enable register field (0xC0[6]) to the value of 1, then while 0xC0[6] has the value of 1, the value in this register field (0xCC[3:0])overrides the master channel you set with the Auto-Negotiation Master parameter. This register field has the following valid values: 4'b0001: Selects Lane 0 4'b0010: Selects Lane 1 4'b0100: Selects Lane 2 4'b1000: Selects Lane 3 All other values are invalid. The new master channel is encoded with one-hot encoding.	4'b0	RW
0x0D0	Reserved	[3:2]	Reserved
	`Ovride LP Coef Enable`	[16]	When set to 1, overrides the link partner's equalization coefficients; software changes the update commands sent to the link partner TX equalizer coefficients. When set to 0, uses the Link Training logic to determine the link partner coefficients. Used with 0x0D1 bits [7:4] and bits[7:0] of 0x0D4 through 0x0D7.	1'b0	RW
	`Ovride Local RX Coef Enable`	[17]	When set to 1, overrides the local device equalization coefficients generation protocol. When set, the software changes the local TX equalizer coefficients. When set to 0, uses the update command received from the link partner to determine local device coefficients. Used with 0x0D1 bits [11:8] and bits[23:16] of 0x0D4 through 0x0D7.	1'b0	RW
	Reserved	[31:22]	Reserved
0x0D1	`Restart Link training, Lane 1`	[1]	When set to 1, resets the 40GBASE-KR4 start-up protocol. When set to 0, continues normal operation. This bit self clears. Refer to the state variable `mr_restart_training` as defined in Clause 72.6.10.3.1 and 10GBASE-KR PMD control register bit (1.150.0) in IEEE Std 802.3ap-2007. Register bit 0xD1[0] refers to Lane 0. This bit is the equivalent of register 0xD1[0] for Lane 1.	1'b0	RW SC
	`Restart Link training, Lane 2`	[2]	This bit is the equivalent of register 0xD1[0] for Lane 2.	1'b0	RW SC
	`Restart Link training, Lane 3`	[3]	This bit is the equivalent of register 0xD0[1] for Lane 3.	1'b0	RW SC
0x0D1	`Updated TX Coef new, Lane 1`	[5]	When set to 1, indicates that new link partner coefficients are available to send. The LT logic starts sending the new values set in 0xD4[7:0] to the remote device. When set to 0, continues normal operation. This bit self clears. This override of normal operation can only occur if 0xD0[16] (`Ovride LP Coef enable`) has the value of 1. If 0xD0[16] has the value of 0, this register field (0xD1[5]) has no effect. Register bit 0xD1[4] refers to Lane 0. This bit is the equivalent of register 0xD1[4] for Lane 1.	1'b0	RW SC
	`Updated TX Coef new, Lane 2`	[6]	This bit is the equivalent of register 0xD1[5] for Lane 2.	1'b0	RW SC
	`Updated TX Coef new, Lane 3`	[7]	This bit is the equivalent of register 0xD1[5] for Lane 3.	1'b0	RW SC
0x0D1	`Updated RX Coef new, Lane 1`	[9]	When set to 1, indicates that new local device coefficients are available for Lane 1. The LT logic changes the local TX equalizer coefficients as specified in 0xE1[23:16]. When set to 0, continues normal operation. This bit self clears. This override of normal operation can only occur if 0xD0[17] (`Ovride Local RX Coef enable`) has the value of 1. If 0xD0[17] has the value of 0, this register field (0xD1[9]) has no effect. Register bit 0xD1[8] refers to Lane 0. This bit is the equivalent of register 0xD1[8] for Lane 1.	1'b0	RW
	`Updated RX Coef new, Lane 2`	[10]	When set to 1, indicates that new local device coefficients are available for Lane 2. The LT logic changes the local TX equalizer coefficients as specified in 0xE5[23:16]. When set to 0, continues normal operation. This bit self clears. This override of normal operation can only occur if 0xD0[17] (`Ovride Local RX Coef enable`) has the value of 1. This bit is the equivalent of register 0xD1[9] for Lane 2.	1'b0	RW
	`Updated RX Coef new, Lane 3`	[11]	When set to 1, indicates that new local device coefficients are available for lane 3. The LT logic changes the local TX equalizer coefficients as specified in 0xE9[23:16]. When set to 0, continues normal operation. This bit self clears. This override of normal operation can only occur if 0xD0[17] (`Ovride Local RX Coef enable`) has the value of 1. This bit is the equivalent of register 0xD1[9] for Lane 3.	1'b0	RW
0x0D2	Reserved	[7:6]	Reserved		RO
		[13:8]	Register bits 0xD2[5:0] refer to Lane 0. These bits are the equivalent of 0xD2[5:0] for Lane 1. For `Link Training Frame lock Error, Lane 1`, if the tap settings specified by the fields of 0xE2 are the same as the initial parameter value, the frame lock error was unrecoverable.		RO
		[21:16]	These bits are the equivalent of 0xD2[5:0] for Lane 2. For `Link Training Frame lock Error, Lane 2`, if the tap settings specified by the fields of 0xE6 are the same as the initial parameter value, the frame lock error was unrecoverable.		RO
		[29:24]	These bits are the equivalent of 0xD2[5:0] for Lane 3. For `Link Training Frame lock Error, Lane 3`, if the tap settings specified by the fields of 0xEA are the same as the initial parameter value, the frame lock error was unrecoverable.		RO
0x0D4	`LD coefficient update[5:0], Lane 0`	[5:0]	Reflects the contents of the first 16-bit word of the training frame sent to Lane 0 from the local device control channel. Normally, the bits in this register are read-only; however, when you override training by setting the `Ovride LP Coef enable` control bit (0x0D0 bit [16]), these bits become writeable. The following fields are defined: [5: 4]: Coefficient (+1) update 2'b11: Reserved 2'b01: Increment 2'b10: Decrement 2'b00: Hold [3:2]: Coefficient (0) update (same encoding as [5:4]) [1:0]: Coefficient (-1) update (same encoding as [5:4]) Before you can send these bits, you must enable the override in 0x0D0 bit [16] and also signal a new word in 0x0D1 bit [4]. For more information, refer to bit 10G BASE-KR LD coefficient update register bits (1.154.5:0) in Clause 45.2.1.80.3 of IEEE 802.3ap-2007.		RO/RW
0x0D4	`LP Coefficient Update[5:0], Lane 0`	[21:16]	Reflects the contents of the first 16-bit word of the training frame most recently received on Lane 0 from the control channel. Normally the bits in this register are read only; however, when training is disabled by setting low the Link Training enable control bit (bit 0 at offset 0xD0), these bits become writeable. The following fields are defined: [5: 4]: Coefficient (+1) update 2'b11: Reserved 2'b01: Increment 2'b10: Decrement 2'b00: Hold [3:2]: Coefficient (0) update (same encoding as [5:4]) [1:0]: Coefficient (-1) update (same encoding as [5:4]) Before you can send these bits, you must enable the override in 0x0D0 bit [17] and also signal a new word in 0x0D2 bit [8]. For more information, refer to bit 10G BASE-KR LP coefficient update register bits (1.152.5:0) in Clause 45.2.1.78.3 of IEEE 802.3ap-2007.
0x0D5	Reserved	[31:21]	Reserved
0x0D6	`LT VODMAX ovrd, Lane 0`	[4:0]	Override value for the VMAXRULE parameter on Lane 0. When enabled, this value substitutes for the VMAXRULE to allow channel-by-channel override of the device settings. This only effects the local device TX output for the channel specified. This value must be greater than the INITMAINVAL parameter for proper operation. Note this will also override the PREMAINVAL parameter value.	0x1C (28 decimal) for simulation; 0 for compilation	RW
	`LT VODMAX ovrd Enable, Lane 0`	[5]	When set to 1, enables the override value for the VMAXRULE parameter stored in the `LT VODMAX ovrd, Lane 0` register field.	1 for simulation; 0 for compilation	RW
	`LT VODMin ovrd, Lane 0`	[12:8]	Override value for the VODMINRULE parameter on Lane 0. When enabled, this value substitutes for the VMINRULE to allow channel-by-channel override of the device settings. This override only effects the local device TX output for this channel. The value to be substituted must be less than the INITMAINVAL parameter and greater than the VMINRULE parameter for proper operation.	0x19 (25 decimal) for simulaton; 0 for compilation	RW
	`LT VODMin ovrd Enable, Lane 0`	[13]	When set to 1, enables the override value for the VODMINRULE parameter stored in the `LT VODMin ovrd, Lane 0` register field.	1 for simulation; 0 for compilation	RW
	`LT VPOST ovrd, Lane 0`	[21:16]	Override value for the VPOSTRULE parameter on Lane 0. When enabled, this value substitutes for the VPOSTRULE to allow channel-by-channel override of the device settings. This override only effects the local device TX output for this channel. The value to be substituted must be greater than the INITPOSTVAL parameter for proper operation.	6 for simulation; 0 for compilation	RW
	`LT VPOST ovrd Enable, Lane 0`	[22]	When set to 1, enables the override value for the VPOSTRULE parameter stored in the `LT VPOST ovrd, Lane 0` register field.	1 for simulation; 0 for compilation	RW
	`LT VPre ovrd, Lane 0`	[28:24]	Override value for the VPRERULE parameter on Lane 0. When enabled, this value substitutes for the VPOSTRULE to allow channel-by-channel override of the device settings. This override only effects the local device TX output for this channel. The value to be substituted must be greater than the INITPREVAL parameter for proper operation.	4 for simulation; 0 for compilation	RW
	`LT VPre ovrd Enable, Lane 0`	[29]	When set to 1, enables the override value for the VPRERULE parameter stored in the `LT VPre ovrd, Lane 0` register field.	1 for simulation; 0 for compilation	RW
0xE0	Register 0xD3 refers to Lane 0. This register, register 0xE0, is the equivalent of register 0xD3 for Lane 1 link training.				RW
0xE1	Register 0xD4 refers to Lane 0. This register, register 0xE1, is the equivalent of register 0xD4 for Lane 1 link training.				RW
0xE2	Register 0xD5 refers to Lane 0. This register, register 0xE2, is the equivalent of register 0xD5 for Lane 1 link training.				RO
0xE3	Register 0xD6 refers to Lane 0. This register, register 0xE3, is the equivalent of register 0xD6 for Lane 1 link training..				RW
0xE4	This register is the equivalent of register 0xD3 for Lane 2 link training.				RW
0xE5	This register is the equivalent of register 0xD4 for Lane 2 link training.				R / RW
0xE6	This register is the equivalent of register 0xD5 for Lane 2 link training.				RO
0xE7	This register is the equivalent of register 0xD6 for Lane 2 link training.				RW
0xE8	This register is the equivalent of register 0xD3 for Lane 3 link training.				RW
0xE9	This register is the equivalent of register 0xD4 for Lane 3 link training.				R / RW
0xEA	This register is the equivalent of register 0xD5 for Lane 3 link training.				RO
0xEB	This register is the equivalent of register 0xD6 for Lane 3 link training.				RW

3.4.1.4. LL 40GbE IP Core MAC Configuration Registers

The MAC configuration registers control the following MAC features in the RX and TX datapaths:

Fault link signaling on the Ethernet link (TX)
Local and remote fault status signals (RX)
CRC forwarding (RX)
Inter-packet gap IDLE removal (TX)
Maximum frame sizes for the CNTR_RX_OVERSIZE and CNTR_TX_OVERSIZE counters (RX and TX)

The fault link signaling and fault status signal registers are documented separately. Refer to Related Links below.

Table 40. TX MAC Configuration Registers This table documents the non-fault link signaling registers in the TX MAC address space. The `LINK_FAULT_CONFIG` register at address 0x405 is documented with the link fault signaling registers. The `LINK_FAULT_CONFIG` register is available only if you turn on Enable link fault generation in the LL 40GbE parameter editor.
Address	Name	Bit	Description	HW Reset Value	Access
0x400	`TXMAC_REVID`	[31:0]	TX MAC revision ID.	0x02062015	RO
0x401	`TXMAC_SCRATCH`	[31:0]	Scratch register available for testing.	32'b0	RW
0x402	`TXMAC_NAME_0`	[31:0]	First 4 characters of IP core variation identifier string "40gMACTxCSR" .		RO
0x403	`TXMAC_NAME_1`	[31:0]	Next 4 characters of IP core variation identifier string "40gMACTxCSR" .		RO
0x404	`TXMAC_NAME_2`	[31:0]	Final 4 characters of IP core variation identifier string "40gMACTxCSR" .		RO
0x406	`IPG_COL_REM`	[7:0]	Specifies the number of IDLE columns to be removed in every Alignment Marker period to compensate for alignment marker insertion. You can program this register to a larger value than the default value, for clock compensation. This register is not present if you set the value of the Average interpacket gap parameter to Disable deficit idle counter in the LL 40GbE parameter editor.	4	RW
0x407	`MAX_TX_SIZE_CONFIG`	[15:0]	Maximum size of Ethernet frames for `CNTR_TX_OVERSIZE`. If the IP core transmits an Ethernet frame of size greater than the number of bytes specified in this register, and the IP core includes TX statistics registers, the IP core increments the 64-bit `CNTR_TX_OVERSIZE` register.	9600 (decimal)	RW

Table 41. RX MAC Configuration Registers This table documents the non-fault link signaling registers in the RX MAC address space. The local and remote fault status register at address 0x508 is documented with the link fault signaling registers. The local and remote fault status register is available only if you turn on Enable link fault generation in the LL 40GbE parameter editor.
Address	Name	Bit	Description	HW Reset Value	Access
0x500	`RXMAC_REVID`	[31:0]	RX MAC revision ID.	0x02062015	RO
0x501	`RXMAC_SCRATCH`	[31:0]	Scratch register available for testing.	32'b0	RW
0x502	`RXMAC_NAME_0`	[31:0]	First 4 characters of IP core variation identifier string "40gMACRxCSR" .		RO
0x503	`RXMAC_NAME_1`	[31:0]	Next 4 characters of IP core variation identifier string "40gMACRxCSR" .		RO
0x504	`RXMAC_NAME_2`	[31:0]	Final 4 characters of IP core variation identifier string "40gMACRxCSR" .		RO
0x506	`MAX_RX_SIZE_CONFIG`	[15:0]	Maximum size of Ethernet frames for `CNTR_RX_OVERSIZE` and for `rx_error[3]` or `l<n>_rx_error[3]` and for .the `RxOctetsOK` register. If the IP core receives an Ethernet frame of size greater than the number of bytes specified in this register, and the IP core includes RX statistics registers, the IP core increments the 64-bit `CNTR_RX_OVERSIZE` register. An Ethernet frame of size greater than the number of bytes specified in this register is considered oversized and therefore does not contribute to the value in the `RxOctetsOK` register.and does cause the assertion of `rx_error[3]` or `l<n>_rx_error[3]`.	9600 (decimal)	RW
0x507	`MAC_CRC_CONFIG`	[0]	The RX CRC forwarding configuration register. Possible values are: 1’b0: remove RX CRC— do not forward it to the RX client interface. 1’b1: retain RX CRC—forward it to the RX client interface. In either case, the IP core checks the incoming RX CRC and flags errors.	1’b0	RW
0x50A	`RXMAC_CONTROL`	[4]	Preamble check. Strict SFD checking option to compare each packet preamble to 0x555555555555. This field is available only if you turn on Enable strict SFD checking .	1'b1	RW
		[3]	SFD check. Strict SFD checking option to compare each SFD byte to 0xD5. This field is available only if you turn on Enable strict SFD checking .	1'b1
		[0]	Enables payload length checking. If you set this bit to the value of 1, bit[4] of the `rx_error` signal flags any payload lengths that do not match the length field.	1'b1

3.4.1.5. Pause Registers

The pause registers together with the pause signals implement the pause functionality defined in the IEEE 802.3ba-2010 High Speed Ethernet Standard. You can program the pause registers to control the insertion and decoding of pause frames, to help reduce traffic in congested networks.

Table 42. TX Ethernet Flow Control (Pause Functionality) Registers Some registers are different depending on whether you select Standard flow control or Priority-based flow control in the LL 40GbE parameter editor. Where the difference is only whether the register refers to the single standard flow control priority class or whether distinct bits in the register refer to the individual priority queues, the two uses are documented together. In that case we understand that standard flow control effectively supports a single priority queue.
When your IP core implements priority-based flow control, the following registers provide an access window into an internal table of values, one per priority queue. The entry currently accessible in the registers is determined by the value you write to the `TX_PAUSE_QNUMBER` register.

`RETRANSMIT_XOFF_HOLDOFF_QUANTA` at offset 0x608

`TX_PAUSE_QUANTA` at offset 0x609
Addr	Name	Bit	Description	HW Reset Value	Access
0x600	`TXSFC_REVID`	[31:0]	TX standard flow control module revision ID.	0x0128_2014	RO
0x601	`TXSFC_SCRATCH`	[31:0]	Scratch register available for testing.	32'b0	RW
0x602	`TXSFC_NAME_0`	[31:0]	First 4 characters of IP core variation identifier string.	0x7843_5352	RO
0x603	`TXSFC_NAME_1`	[31:0]	Next 4 characters of IP core variation identifier string.	0x5054_5054	RO
0x604	`TXSFC_NAME_2`	[31:0]	Final 4 characters of IP core variation identifier string.	0x3034_3067	RO
0x605	`TX_PAUSE_EN`	[N-1:0] ⁷	Enable the IP core to transmit pause frames on the Ethernet link in response to a client request through the `pause_insert_tx` input signal or the `TX_PAUSE_REQUEST` register. If your IP core implements priority-based flow control, each bit of this field enables TX pause functionality for the corresponding priority queue. Intel recommends that you signal a pause request using the `pause_insert_tx` signal rather than using the `TX_PAUSE_REQUEST` register.	N'b1 ...1 (1'b1 in each defined bit)	RW
0x606	`TX_PAUSE_REQUEST`	[N-1:0]⁷	Pause request. If bit [n] of the `TX_PAUSE_EN` register has the value of 1, setting bit [n] of the `TX_PAUSE_REQUEST` register field to the value of 1 triggers a XOFF pause packet insertion into the TX data stream on the Ethernet link. If the IP core implements priority-based flow control, the XOFF pause packet includes identity information for the corresponding priority queue. If `RETRANSMIT_XOFF_HOLDOFF_EN` is turned on for the associated priority queue, as long as the value in `TX_PAUSE_REQUEST` bit [n] remains high, the IP core retransmits the XOFF pause packet at intervals determined by the retransmit hold-off value associated with this priority queue. If bit [n] of the `TX_PAUSE_EN` register has the value of 1, resetting bit [n] of the `TX_PAUSE_REQUEST` register field to the value of 0 triggers an XON pause packet insertion into the TX data stream on the Ethernet link. If the IP core implements priority-based flow control, the XON pause packet includes identity information for the corresponding priority queue. Other pause registers, described in this table, specify the properties of the pause packets. Intel recommends that you signal a pause request using the `pause_insert_tx` signal rather than using the `TX_PAUSE_REQUEST` register.	0	RW
0x607	`RETRANSMIT_XOFF_HOLDOFF_EN`	[N-1:0] ⁷	Enable XOFF pause frame retransmission hold-off functionality. If your IP core implements priority-based flow control with multiple priority queues, this register provides access to one bit for each priority queue. Intel recommends that you maintain this register at the value of all ones. If your IP core implements priority-based flow control, refer also to the description of the `CFG_RETRANSMIT_HOLDOFF_EN` and `CFG_RETRANSMIT_HOLDOFF_QUANTA` registers.	N'b1...1 (1'b1 in each defined bit)	RW
0x608	`RETRANSMIT_XOFF_HOLDOFF_QUANTA`	[15:0]	Specifies hold-off time from XOFF pause frame transmission until retransmission, if retransmission hold-off functionality is enabled and pause request remains at the value of 1. If your IP core implements priority-based flow control with multiple priority queues, this register provides access to an internal table of retransmit-hold-off times, one for each priority queue. Accesses are indexed by the value in the `TX_PAUSE_QNUMBER` register. Unit is quanta. One quanta is 512 bit times, which depends on the datapath width (256 bits) and the `clk_txmac` frequency. Pause request can be either of the `TX_PAUSE_REQUEST` register pause request bit and the `pause_insert_tx` signal.	0xFFFF	RW
0x609	`TX_PAUSE_QUANTA`	[15:0]	Specifies the pause time to be included in XOFF frames. If your IP core implements priority-based flow control with multiple priority queues, this register provides access to an internal table of pause times, one for each priority queue. Accesses are indexed by the value in the `TX_PAUSE_QNUMBER` register. Unit is quanta. One quanta is 512 bit times, which depends on the datapath width (256 bits) and the `clk_txmac` frequency.	0xFFFF	RW
0x60A if you set the value of Flow control mode to Standard flow control in the LL 40GbEparameter editor.	`TX_XOF_EN`	[0]	Enable the TX MAC to pause outgoing Ethernet traffic in response to a pause frame received on the RX Ethernet link and forwarded to the TX MAC by the RX MAC. If the `cfg_enable` bit of the `RX_PAUSE_ENABLE` register has the value of 1, the RX MAC processes incoming pause frames. When the RX MAC processes an incoming pause frame with an address match, it notifies the TX MAC to pause outgoing traffic on the TX Ethernet link. The TX MAC pauses outgoing traffic on the TX Ethernet link in response to this notification only if bit [0] of the `TX_XOF_EN` register has the value of 1. The value in the `TX_XOF_EN` register is only relevant when the `cfg_enable` bit of the `RX_PAUSE_ENABLE` register has the value of 1. If the `cfg_enable` bit of the `RX_PAUSE_ENABLE` register has the value of 0, pause frames received on the RX Ethernet link do not reach the TX MAC.	1'b0	RW
0x60A if you set the value of Flow control mode to Priority-based flow control in the LL 40GbEparameter editor.	`TX_PAUSE_QNUMBER`	[2:0]	Queue number (index to internal table) of queue whose relevant values are currently accessible (readable and writeable) in these registers: `RETRANSMIT_XOFF_HOLDOFF_QUANTA` at offset 0x608 `TX_PAUSE_QUANTA` at offset 0x609	0	RW
0x60B	`CFG_RETRANSMIT_HOLDOFF_EN`	[0]	The `CFG_RETRANSMIT_HOLDOFF_EN` and `CFG_RETRANSMIT_HOLDOFF_QUANTA` registers provide a mechanism to specify a uniform retransmission hold-off delay for all priority queues. If `CFG_RETRANSMIT_HOLDOFF_EN` has the value of 1, the IP core enforces a retransmission hold-off delay for each priority queue that is the longer of the queue-specific retransmission hold-off delay accessible in the `RETRANSMIT_XOFF_HOLDOFF_QUANTA` register (if enabled) and the retransmission hold-off delay specified in the `CFG_RETRANSMIT_HOLDOFF_QUANTA` register. `CFG_RETRANSMIT_HOLDOFF_QUANTA` unit is quanta. One quanta is 512 bit times, which depends on the datapath width (256 bits) and the `clk_txmac` frequency. These registers are present only if you set the value of Flow control mode to Priority-based flow control in the LL 40GbE parameter editor.	1'b0	RW
0x60C	`CFG_RETRANSMIT_HOLDOFF_QUANTA`	[15:0]
0x60D	`TX_PFC_DADDRL`	[31:0]	`TX_PFC_DADDRH` contains the 16 most significant bits of the destination address for PFC pause frames. `TX_PFC_DADDRL` contains the 32 least significant bits of the destination address for PFC pause frames. This feature allows you to program a destination address other than the standard multicast address for PFC frames, for debug or proprietary purposes. `{TX_PFC_DADDRH[15:0],TX_PFC_DADDRL[31:0]}` can be a broadcast, muilticast, or unicast address. These registers are present only if you set the value of Flow control mode to Priority-based flow control in the LL 40GbE parameter editor.	0xC200_0001	RW
0x60E	`TX_PFC_DADDRH`	[15:0]		0x0180	RW
0x60F	`TX_PFC_SADDRL`	[31:0]	`TX_PFC_SADDRH` contains the 16 most significant bits of the source address for PFC pause frames. `TX_PFC_SADDRL` contains the 32 least significant bits of the source address for PFC pause frames. These registers are present only if you set the value of Flow control mode to Priority-based flow control in the LL 40GbE parameter editor.	0xCBFC_5ADD	RW
0x610	`TX_PFC_SADDRH`	[15:0]		0xE100	RW

Table 43. RX Ethernet Flow Control (Pause Functionality) Registers Some registers are different depending on whether you select Standard flow control or Priority-based flow control in the LL 40GbE parameter editor. Where the difference is only whether the register refers to the single standard flow control priority class or whether distinct bits in the register refer to the individual priority queues, the two uses are documented together. In that case we understand that standard flow control effectively supports a single priority queue.
Addr	Name	Bit	Description	HW Reset Value	Access
0x700	`RXSFC_REVID`	[31:0]	RX standard flow control module revision ID.	0x0128_2014	RO
0x701	`RXSFC_SCRATCH`	[31:0]	Scratch register available for testing.	32'b0	RW
0x702	`RXSFC_NAME_0`	[31:0]	First 4 characters of IP core variation identifier string.	0x7843_5352	RO
0x703	`RXSFC_NAME_1`	[31:0]	Next 4 characters of IP core variation identifier string.	0x5054_5054	RO
0x704	`RXSFC_NAME_2`	[31:0]	Final 4 characters of IP core variation identifier string.	0x3034_3067	RO
0x705	`RX_PAUSE_ENABLE`	[N-1:0]	`cfg_enable` bits. When bit [n] has the value of 1, the RX MAC processes the incoming pause frames for priority class n whose address matches {DADDR1[31:0],DADDR0[15:0]}. When bit [n] has the value of 0, the RX MAC does not process any incoming pause frames for priority class n. When the RX MAC processes an incoming pause frame with an address match, it notifies the TX MAC to pause outgoing traffic on the TX Ethernet link. If you implement priority-based flow control, the TX MAC pauses outgoing traffic from the indicated priority queue to the TX Ethernet link in response to this notification. If you implement standard flow control, the TX MAC pauses outgoing traffic on the TX Ethernet link in response to this notification only if bit [0] of the `TX_XOF_EN` register has the value of 1.	N'b1...1 (1'b1 in each defined bit)	RW
0x706	`RX_PAUSE_FWD`	[0]	`cfg_fwd_ctrl` bit. When this bit has the value of 1, the RX MAC forwards matching pause frames to the RX client interface. When this bit has the value of 0, the RX MAC does not forward matching pause frames to the RX client interface. In both cases, the RX MAC forwards non-matching pause frames to the RX client interface.	1'b0	RW
0x707	`RX_PAUSE_DADDRL`	[31:0]	`RX_PAUSE_DADDRL` contains the 32 least significant bits of the destination address for pause frame matching. `RX_PAUSE_DADDRH` contains the 16 most significant bits of the destination address for pause frame matching. When pause frame processing is turned on, if `{RX_PAUSE_DADDRH[15:0],RX_PAUSE_DADDRL[31:0]}` matches the incoming pause frame destination address, the IP core processes the pause frame. if there is no match, the IP core does not process the pause frame. `{RX_PAUSE_DADDRH[15:0],RX_PAUSE_DADDRL[31:0]}` can be a broadcast, muilticast, or unicast address.	0xC200_0001	RW
0x708	`RX_PAUSE_DADDRH`	[15:0]		0x0180	RW

⁷ N is the number of priority queues. If the IP core implements Ethernet standard flow control, N is 1.

3.4.1.6. TX Statistics Registers

The TX statistics registers count TX Ethernet traffic and errors. The 64-bit statistics registers are designed to roll over, to ensure timing closure on the FPGA. However, these registers should never roll over if the link is functioning properly. The statistics registers check the size of frames, which includes the following fields:

Size of the destination address
Size of the source address
Size of the data
Four bytes of CRC

The TX statistics counters module is a synthesis option. The statistics registers are counters that are implemented inside the CSR. When you turn on the Enable TX statistics parameter in the LL 40GbE parameter editor, the counters are implemented in the CSR. When you turn off the Enable TX statistics parameter in the LL 40GbE parameter editor, the counters are not implemented in the CSR, and read access to the counters returns read data equal to 0.

Reading the value of a statistics register does not affect its value. A configuration register at offset 0x845 allows you to clear all of the TX statistics counters.

To ensure that the counters you read are consistent, you should issue a shadow request to create a snapshot of all of the TX statistics registers, by setting bit [2] of the configuration register at offset 0x845. Until you reset this bit, the counters continue to increment but the readable values remain constant.

Table 44. Transmit Side Statistics Registers
Address	Name-	Description	Access
0x800	`CNTR_TX_FRAGMENTS_LO`	Number of transmitted frames less than 64 bytes and reporting a CRC error (lower 32 bits)	RO
0x801	`CNTR_TX_FRAGMENTS_HI`	Number of transmitted frames less than 64 bytes and reporting a CRC error (upper 32 bits)	RO
0x802	`CNTR_TX_JABBERS_LO`	Number of transmitted oversized frames reporting a CRC error (lower 32 bits)	RO
0x803	`CNTR_TX_JABBERS_HI`	Number of transmitted oversized frames reporting a CRC error (upper 32 bits)	RO
0x804	`CNTR_TX_FCS_LO`	Number of transmitted packets with FCS errors. (lower 32 bits)	RO
0x805	`CNTR_TX_FCS_HI`	Number of transmitted packets with FCS errors. (upper 32 bits)	RO
0x806	`CNTR_TX_CRCERR_LO`	Number of transmitted frames with a frame of length at least 64 reporting a CRC error (lower 32 bits)	RO
0x807	`CNTR_TX_CRCERR_HI`	Number of transmitted frames with a frame of length at least 64 reporting a CRC error (upper 32 bits)	RO
0x808	`CNTR_TX_MCAST_DATA_ERR_LO`	Number of errored multicast frames transmitted, excluding control frames (lower 32 bits)	RO
0x809	`CNTR_TX_MCAST_DATA_ERR_HI`	Number of errored multicast frames transmitted, excluding control frames (upper 32 bits)	RO
0x80A	`CNTR_TX_BCAST_DATA_ERR_LO`	Number of errored broadcast frames transmitted, excluding control frames (lower 32 bits)	RO
0x80B	`CNTR_TX_BCAST_DATA_ERR_HI`	Number of errored broadcast frames transmitted, excluding control frames (upper 32 bits)	RO
0x80C	`CNTR_TX_UCAST_DATA_ERR_LO`	Number of errored unicast frames transmitted, excluding control frames (lower 32 bits)	RO
0x80D	`CNTR_TX_UCAST_DATA_ERR_HI`	Number of errored unicast frames transmitted, excluding control frames (upper 32 bits)	RO
0x80E	`CNTR_TX_MCAST_CTRL_ERR_LO`	Number of errored multicast control frames transmitted (lower 32 bits)	RO
0x80F	`CNTR_TX_MCAST_CTRL_ERR_HI`	Number of errored multicast control frames transmitted (upper 32 bits)	RO
0x810	`CNTR_TX_BCAST_CTRL_ERR_LO`	Number of errored broadcast control frames transmitted (lower 32 bits)	RO
0x811	`CNTR_TX_BCAST_CTRL_ERR_HI`	Number of errored broadcast control frames transmitted (upper 32 bits)	RO
0x812	`CNTR_TX_UCAST_CTRL_ERR_LO`	Number of errored unicast control frames transmitted (lower 32 bits)	RO
0x813	`CNTR_TX_UCAST_CTRL_ERR_HI`	Number of errored unicast control frames transmitted (upper 32 bits)	RO
0x814	`CNTR_TX_PAUSE_ERR_LO`	Number of errored pause frames transmitted (lower 32 bits)	RO
0x815	`CNTR_TX_PAUSE_ERR_HI`	Number of errored pause frames transmitted (upper 32 bits)	RO
0x816	`CNTR_TX_64B_LO`	Number of 64-byte transmitted frames (lower 32 bits), including the CRC field but excluding the preamble and SFD bytes	RO
0x817	`CNTR_TX_64B_HI`	Number of 64-byte transmitted frames (upper 32 bits), including the CRC field but excluding the preamble and SFD bytes	RO
0x818	`CNTR_TX_65to127B_LO`	Number of transmitted frames between 65–127 bytes (lower 32 bits)	RO
0x819	`CNTR_TX_65to127B_HI`	Number of transmitted frames between 65–127 bytes (upper 32 bits)	RO
0x81A	`CNTR_TX_128to255B_LO`	Number of transmitted frames between 128 –255 bytes (lower 32 bits)	RO
0x81B	`CNTR_TX_128to255B_HI`	Number of transmitted frames between 128 –255 bytes (upper 32 bits)	RO
0x81C	`CNTR_TX_256to511B_LO`	Number of transmitted frames between 256 –511 bytes (lower 32 bits)	RO
0x81D	`CNTR_TX_256to511B_HI`	Number of transmitted frames between 256 –511 bytes (upper 32 bits)	RO
0x81E	`CNTR_TX_512to1023B_LO`	Number of transmitted frames between 512–1023 bytes (lower 32 bits)	RO
0x81F	`CNTR_TX_512to1023B_HI`	Number of transmitted frames between 512 –1023 bytes (upper 32 bits)	RO
0x820	`CNTR_TX_1024to1518B_LO`	Number of transmitted frames between 1024–1518 bytes (lower 32 bits)	RO
0x821	`CNTR_TX_1024to1518B_HI`	Number of transmitted frames between 1024–1518 bytes (upper 32 bits)	RO
0x822	`CNTR_TX_1519toMAXB_LO`	Number of transmitted frames of size between 1519 bytes and the number of bytes specified in the `MAX_TX_SIZE_CONFIG` register (lower 32 bits)	RO
0x823	`CNTR_TX_1519toMAXB_HI`	Number of transmitted frames of siz between 1519 bytes and the number of bytes specified in the `MAX_TX_SIZE_CONFIG` register (upper 32 bits)	RO
0x824	`CNTR_TX_OVERSIZE_LO`	Number of oversized frames (frames with more bytes than the number specified in the `MAX_TX_SIZE_CONFIG` register) transmitted (lower 32 bits)	RO
0x825	`CNTR_TX_OVERSIZE_HI`	Number of oversized frames (frames with more bytes than the number specified in the `MAX_TX_SIZE_CONFIG` register) transmitted (upper 32 bits)	RO
0x826	`CNTR_TX_MCAST_DATA_OK_LO`	Number of valid multicast frames transmitted, excluding control frames (lower 32 bits)	RO
0x827	`CNTR_TX_MCAST_DATA_OK_HI`	Number of valid multicast frames transmitted, excluding control frames (upper 32 bits)	RO
0x828	`CNTR_TX_BCAST_DATA_OK_LO`	Number of valid broadcast frames transmitted, excluding control frames (lower 32 bits)	RO
0x829	`CNTR_TX_BCAST_DATA_OK_HI`	Number of valid broadcast frames transmitted, excluding control frames (upper 32 bits)	RO
0x82A	`CNTR_TX_UCAST_DATA_OK_LO`	Number of valid unicast frames transmitted, excluding control frames (lower 32 bits)	RO
0x82B	`CNTR_TX_UCAST_DATA_OK_HI`	Number of valid unicast frames transmitted, excluding control frames (upper 32 bits)	RO
0x82C	`CNTR_TX_MCAST_CTRL_LO`	Number of valid multicast frames transmitted, excluding data frames (lower 32 bits)	RO
0x82D	`CNTR_TX_MCAST_CTRL_HI`	Number of valid multicast frames transmitted, excluding data frames (upper 32 bits)	RO
0x82E	`CNTR_TX_BCAST_CTRL_LO`	Number of valid broadcast frames transmitted, excluding data frames (lower 32 bits)	RO
0x82F	`CNTR_TX_BCAST_CTRL_HI`	Number of valid broadcast frames transmitted, excluding data frames (upper 32 bits)	RO
0x830	`CNTR_TX_UCAST_CTRL_LO`	Number of valid unicast frames transmitted, excluding data frames (lower 32 bits)	RO
0x831	`CNTR_TX_UCAST_CTRL_HI`	Number of valid unicast frames transmitted, excluding data frames (upper 32 bits)	RO
0x832	`CNTR_TX_PAUSE_LO`	Number of valid pause frames transmitted (lower 32 bits)	RO
0x833	`CNTR_TX_PAUSE_HI`	Number of valid pause frames transmitted (upper 32 bits)	RO
0x834	`CNTR_TX_RUNT_LO`	Number of transmitted runt packets (lower 32 bits). The IP core does not transmit frames of length less than nine bytes. The IP core pads frames of length nine bytes to 64 bytes to extend them to 64 bytes.	RO
0x835	`CNTR_TX_RUNT_HI`	Number of transmitted runt packets (upper 32 bits). The IP core does not transmit frames of length less than nine bytes. The IP core pads frames of length nine bytes to 64 bytes to extend them to 64 bytes.	RO
0x836	`CNTR_TX_ST_LO`	Number of transmitted frame starts (lower 32 bits)	RO
0x837	`CNTR_TX_ST_HI`	Number of transmitted frame starts (upper 32 bits)	RO
0x838–0x83F	Reserved
0x840	`TXSTAT_REVID`	TX statistics module revision ID.	RO
0x841	`TXSTAT_SCRATCH`	Scratch register available for testing. Default value is 0x08.	RW
0x842	`TXSTAT_NAME_0`	First 4 characters of IP core variation identifier string "040gMacStats"	RO
0x843	`TXSTAT_NAME_1`	Next 4 characters of IP core variation identifier string "040gMacStats"	RO
0x844	`TXSTAT_NAME_2`	Final 4 characters of IP core variation identifier string "040gMacStats"	RO
0x845	`CNTR_TX_CONFIG`	Bits [2:0]: Configuration of TX statistics counters: Bit [2]: Shadow request (active high): When set to the value of 1, TX statistics collection is paused. The underlying counters continue to operate, but the readable values reflect a snapshot at the time the pause flag was activated. Write a 0 to release. Bit [1]: Parity-error clear. When software sets this bit, the IP core clears the parity bit `CNTR_TX_STATUS[0]`. This bit (`CNTR_TX_CONFIG[1]`) is self-clearing. Bit [0]: Software can set this bit to the value of 1 to reset all of the TX statistics registers at the same time. This bit is self-clearing. Bits [31:3] are Reserved.	RW
0x846	`CNTR_TX_STATUS`	Bit [1]: Indicates that the TX statistics registers are paused (while `CNTR_TX_CONFIG[2]` is asserted) . Bit [0]: Indicates the presence of at least one parity error in the TX statistics counters. Bits [31:2] are Reserved.	RO
0x860	TxOctetsOK_LO	Number of transmitted payload bytes in frames with no FCS, undersized, oversized, or payload length errors. This register is compliant with section 5.2.2.18 of the IEEE Standard 802.3-2008. This register corresponds to the signals `tx_inc_octetsOK[15:0]` and `tx_inc_octetsOK_valid`.	RO
0x861	TxOctetsOK_HI		RO

3.4.1.7. RX Statistics Registers

The RX statistics registers count RX Ethernet traffic and errors. The 64-bit statistics registers are designed to roll over, to ensure timing closure on the FPGA. However, these registers should never roll over if the link is functioning properly. The statistics registers check the size of frames, which includes the following fields:

Size of the destination address
Size of the source address
Size of the data
Four bytes of CRC

The RX statistics counters module is a synthesis option. The statistics registers are counters that are implemented inside the CSR. When you turn on the Enable RX statistics parameter in the LL 40GbE parameter editor, the counters are implemented in the CSR. When you turn off the Enable RX statistics parameter in the LL 40GbE parameter editor, the counters are not implemented in the CSR, and read access to the counters returns read data equal to 0.

Reading the value of a statistics register does not affect its value. A configuration register at offset 0x945 allows you to clear all of the RX statistics counters.

To ensure that the counters you read are consistent, you should issue a shadow request to create a snapshot of all of the RX statistics registers, by setting bit [2] of the configuration register at offset 0x945. Until you reset this bit, the counters continue to increment but the readable values remain constant.

Table 45. Receive Side Statistics Registers
Address	Name-	Description	Access
0x900	`CNTR_RX_FRAGMENTS_LO`	Number of received frames less than 64 bytes and reporting a CRC error (lower 32 bits)	RO
0x901	`CNTR_RX_FRAGMENTS_HI`	Number of received frames less than 64 bytes and reporting a CRC error (upper 32 bits)	RO
0x902	`CNTR_RX_JABBERS_LO`	Number of received oversized frames reporting a CRC error (lower 32 bits)	RO
0x903	`CNTR_RX_JABBERS_HI`	Number of received oversized frames reporting a CRC error (upper 32 bits)	RO
0x904	`CNTR_RX_FCS_LO`	Number of received packets with FCS errors. This register maintains a count of the number of pulses on the `l<n>_rx_fcs_error` or `rx_fcs_error` output signal (lower 32 bits)	RO
0x905	`CNTR_RX_FCS_HI`	Number of received packets with FCS errors. This register maintains a count of the number of pulses on the `l<n>_rx_fcs_error` output signal (upper 32 bits)	RO
0x906	`CNTR_RX_CRCERR_LO`	Number of received frames with a frame of length at least 64, with CRC error (lower 32 bits)	RO
0x907	`CNTR_RX_CRCERR_HI`	Number of received frames with a frame of length at least 64, with CRC error (upper 32 bits)	RO
0x908	`CNTR_RX_MCAST_DATA_ERR_LO`	Number of errored multicast frames received, excluding control frames (lower 32 bits)	RO
0x909	`CNTR_RX_MCAST_DATA_ERR_HI`	Number of errored multicast frames received, excluding control frames (upper 32 bits)	RO
0x90A	`CNTR_RX_BCAST_DATA_ERR_LO`	Number of errored broadcast frames received, excluding control frames (lower 32 bits)	RO
0x90B	`CNTR_RX_BCAST_DATA_ERR_HI`	Number of errored broadcast frames received, excluding control frames (upper 32 bits)	RO
0x90C	`CNTR_RX_UCAST_DATA_ERR_LO`	Number of errored unicast frames received, excluding control frames (lower 32 bits)	RO
0x90D	`CNTR_RX_UCAST_DATA_ERR_HI`	Number of errored unicast frames received, excluding control frames (upper 32 bits)	RO
0x90E	`CNTR_RX_MCAST_CTRL_ERR_LO`	Number of errored multicast control frames received (lower 32 bits)	RO
0x90F	`CNTR_RX_MCAST_CTRL_ERR_HI`	Number of errored multicast control frames received (upper 32 bits)	RO
0x910	`CNTR_RX_BCAST_CTRL_ERR_LO`	Number of errored broadcast control frames received (lower 32 bits)	RO
0x911	`CNTR_RX_BCAST_CTRL_ERR_HI`	Number of errored broadcast control frames received (upper 32 bits)	RO
0x912	`CNTR_RX_UCAST_CTRL_ERR_LO`	Number of errored unicast control frames received (lower 32 bits)	RO
0x913	`CNTR_RX_UCAST_CTRL_ERR_HI`	Number of errored unicast control frames received (upper 32 bits)	RO
0x914	`CNTR_RX_PAUSE_ERR_LO`	Number of errored pause frames received (lower 32 bits)	RO
0x915	`CNTR_RX_PAUSE_ERR_HI`	Number of errored pause frames received (upper 32 bits)	RO
0x916	`CNTR_RX_64B_LO`	Number of 64-byte received frames (lower 32 bits), including the CRC field but excluding the preamble and SFD bytes	RO
0x917	`CNTR_RX_64B_HI`	Number of 64-byte received frames (upper 32 bits), including the CRC field but excluding the preamble and SFD bytes	RO
0x918	`CNTR_RX_65to127B_LO`	Number of received frames between 65–127 bytes (lower 32 bits)	RO
0x919	`CNTR_RX_65to127B_HI`	Number of received frames between 65–127 bytes (upper 32 bits)	RO
0x91A	`CNTR_RX_128to255B_LO`	Number of received frames between 128 –255 bytes (lower 32 bits)	RO
0x91B	`CNTR_RX_128to255B_HI`	Number of received frames between 128 –255 bytes (upper 32 bits)	RO
0x91C	`CNTR_RX_256to511B_LO`	Number of received frames between 256 –511 bytes (lower 32 bits)	RO
0x91D	`CNTR_RX_256to511B_HI`	Number of received frames between 256 –511 bytes (upper 32 bits)	RO
0x91E	`CNTR_RX_512to1023B_LO`	Number of received frames between 512–1023 bytes (lower 32 bits)	RO
0x91F	`CNTR_RX_512to1023B_HI`	Number of received frames between 512 –1023 bytes (upper 32 bits)	RO
0x920	`CNTR_RX_1024to1518B_LO`	Number of received frames between 1024–1518 bytes (lower 32 bits)	RO
0x921	`CNTR_RX_1024to1518B_HI`	Number of received frames between 1024–1518 bytes (upper 32 bits)	RO
0x922	`CNTR_RX_1519toMAXB_LO`	Number of received frames between 1519 bytes and the maximum size defined in the `MAX_RX_SIZE_CONFIG` register (lower 32 bits)	RO
0x923	`CNTR_RX_1519toMAXB_HI`	Number of received frames between 1519 bytes and the maximum size defined in the `MAX_RX_SIZE_CONFIG` register (upper 32 bits)	RO
0x924	`CNTR_RX_OVERSIZE_LO`	Number of oversized frames (frames with more bytes than the number specified in the `MAX_RX_SIZE_CONFIG` register) received (lower 32 bits)	RO
0x925	`CNTR_RX_OVERSIZE_HI`	Number of oversized frames (frames with more bytes than the number specified in the `MAX_RX_SIZE_CONFIG` register) received (upper 32 bits)	RO
0x926	`CNTR_RX_MCAST_DATA_OK_LO`	Number of valid multicast frames received, excluding control frames (lower 32 bits)	RO
0x927	`CNTR_RX_MCAST_DATA_OK_HI`	Number of valid multicast frames received, excluding control frames (upper 32 bits)	RO
0x928	`CNTR_RX_BCAST_DATA_OK_LO`	Number of valid broadcast frames received, excluding control frames (lower 32 bits)	RO
0x929	`CNTR_RX_BCAST_DATA_OK_HI`	Number of valid broadcast frames received, excluding control frames (upper 32 bits)	RO
0x92A	`CNTR_RX_UCAST_DATA_OK_LO`	Number of valid unicast frames received, excluding control frames (lower 32 bits)	RO
0x92B	`CNTR_RX_UCAST_DATA_OK_HI`	Number of valid unicast frames received, excluding control frames (upper 32 bits)	RO
0x92C	`CNTR_RX_MCAST_CTRL_LO`	Number of valid multicast frames received, excluding data frames (lower 32 bits)	RO
0x92D	`CNTR_RX_MCAST_CTRL_HI`	Number of valid multicast frames received, excluding data frames (upper 32 bits)	RO
0x92E	`CNTR_RX_BCAST_CTRL_LO`	Number of valid broadcast frames received, excluding data frames (lower 32 bits)	RO
0x92F	`CNTR_RX_BCAST_CTRL_HI`	Number of valid broadcast frames received, excluding data frames (upper 32 bits)	RO
0x930	`CNTR_RX_UCAST_CTRL_LO`	Number of valid unicast frames received, excluding data frames (lower 32 bits)	RO
0x931	`CNTR_RX_UCAST_CTRL_HI`	Number of valid unicast frames received, excluding data frames (upper 32 bits)	RO
0x932	`CNTR_RX_PAUSE_LO`	Number of valid pause frames received (lower 32 bits)	RO
0x933	`CNTR_RX_PAUSE_HI`	Number of valid pause frames received (upper 32 bits)	RO
0x934	`CNTR_RX_RUNT_LO`	Number of received runt packets (lower 32 bits) A run is a packet of size less than 64 bytes but greater than eight bytes. If a packet is eight bytes or smaller, it is considered a decoding error and not a runt frame, and the IP core does not flag it nor count it as a runt.	RO
0x935	`CNTR_RX_RUNT_HI`	Number of received runt packets (upper 32 bits) A run is a packet of size less than 64 bytes but greater than eight bytes. If a packet is eight bytes or smaller, it is considered a decoding error and not a runt frame, and the IP core does not flag it nor count it as a runt.	RO
0x936	`CNTR_RX_ST_LO`	Number of received frame starts (lower 32 bits)	RO
0x937	`CNTR_RX_ST_HI`	Number of received frame starts (upper 32 bits)	RO