V-Series Avalon-MM DMA Interface for PCIe Solutions User Guide

ID 683514
Date 7/31/2018
Public
Document Table of Contents

Refer to Reset and Clocks for more information about the reset sequence and a block diagram of the reset logic.

Reset Signals

Signal

Direction

Description

npor

Input

Active low reset signal. In the Intel hardware example designs, npor is the OR of pin_perst and local_rstn coming from the software Application Layer. If you do not drive a soft reset signal from the Application Layer, this signal must be derived from pin_perst. You cannot disable this signal. Resets the entire IP Core and transceiver. Asynchronous.

In systems that use the hard reset controller, this signal is edge, not level sensitive; consequently, you cannot use a low value on this signal to hold custom logic in reset. For more information about the hard and soft reset controllers, refer to Reset.

nreset_status

Output

Active low reset signal. It is derived from npor or pin_perstn. You can use this signal to reset the Application Layer.
pin_perst

Input

Active low reset from the PCIe reset pin of the device. pin_perst resets the datapath and control registers. This signal is required for Configuration via Protocol (CvP). For more information about CvP refer to Configuration via Protocol (CvP).

V-Series have 1 or 2 instances of the Hard IP for PCI Express. Each instance has its own pin_perst signal. You must connect the pin_perst of each Hard IP instance to the corresponding nPERST pin of the device. These pins have the following locations:

For Arria V devices:

  • nPERSTL0: bottom left Hard IP block and CvP blocks
  • nPERSTL1: top left Hard IP

For Cyclone V devices:

  • nPERSTL0: top left Hard IP
  • nPERSTL1: bottom left Hard IP and CvP blocks

For Arria V GZ and Stratix V devices:

  • NPERSTL0: bottom left Hard IP and CvP blocks
  • NPERSTL1: top left Hard IP block
  • NPERSTR0: bottom right Hard IP block
  • NPERSTR1: top right Hard IP block

For maximum use of the V-Series device, Intel recommends that you use the bottom left Hard IP first. This is the only location that supports CvP over a PCIe link.

Refer to the appropriate device pinout for correct pin assignment for more detailed information about these pins. The PCI Express Card Electromechanical Specification 2.0 specifies this pin requires 3.3 V. You can drive this 3.3V signal to the nPERST* even if the VVCCPGM of the bank is not 3.3V if the following 2 conditions are met:

  • The input signal meets the VIH and VIL specification for LVTTL.

    The input signal meets the overshoot specification for 100°C operation as specified by the Maximum Allowed Overshoot and Undershoot Voltage in the device datasheet.

Reset and Link Training Timing Relationships

The following figure illustrates the timing relationship between npor and the LTSSM L0 state.

Note: To meet the 100 ms system configuration time, you must use the fast passive parallel configuration scheme with CvP and a 32-bit data width (FPP x32) or use the V-Series Hard IP for PCI Express in autonomous mode.
Status and Link Training Signals

Signal

Direction

Description

cfg_par_err

Output

Indicates that a parity error in a TLP routed to the internal Configuration Space. This error is also logged in the Vendor Specific Extended Capability internal error register. You must reset the Hard IP if this error occurs.

The signal is not available for Arria V and Cyclone V devices.

derr_cor_ext_rcv

Output

Indicates a corrected error in the RX buffer. This signal is for debug only. It is not valid until the RX buffer is filled with data. This is a pulse, not a level, signal. Internally, the pulse is generated with the 500 MHz clock. A pulse extender extends the signal so that the FPGA fabric running at 250 MHz can capture it. Because the error was corrected by the IP core, no Application Layer intervention is required.

derr_cor_ext_rpl

Output

Indicates a corrected ECC error in the retry buffer. This signal is for debug only. Because the error was corrected by the IP core, no Application Layer intervention is required.

derr_rpl

Output

Indicates an uncorrectable error in the retry buffer. This signal is for debug only.

The signal is not available for Arria V and Cyclone V devices.

dlup_exit

Output

This signal is asserted low for one pld_clk cycle when the IP core exits the DLCMSM DL_Up state, indicating that the Data Link Layer has lost communication with the other end of the PCIe link and left the Up state. When this pulse is asserted, the Application Layer should generate an internal reset signal that is asserted for at least 32 cycles.

ev128ns

Output

Asserted every 128 ns to create a time base aligned activity.

ev1us

Output

Asserted every 1µs to create a time base aligned activity.

hotrst_exit

Output

Hot reset exit. This signal is asserted for 1 clock cycle when the LTSSM exits the hot reset state. This signal should cause the Application Layer to be reset. This signal is active low. When this pulse is asserted, the Application Layer should generate an internal reset signal that is asserted for at least 32 cycles.

int_status[3:0]

Output

These signals drive legacy interrupts to the Application Layer as follows:

  • int_status[0]: interrupt signal A
  • int_status[1]: interrupt signal B
  • int_status[2]: interrupt signal C
  • int_status[3]: interrupt signal D
ko_cpl_spc_data[11:0]

Output

The Application Layer can use this signal to build circuitry to prevent RX buffer overflow for completion data. Endpoints must advertise infinite space for completion data; however, RX buffer space is finite. ko_cpl_spc_data is a static signal that reflects the total number of 16 byte completion data units that can be stored in the completion RX buffer.

ko_cpl_spc_header[7:0]

Output

The Application Layer can use this signal to build circuitry to prevent RX buffer overflow for completion headers. Endpoints must advertise infinite space for completion headers; however, RX buffer space is finite. ko_cpl_spc_header is a static signal that indicates the total number of completion headers that can be stored in the RX buffer.

l2_exit

Output

L2 exit. This signal is active low and otherwise remains high. It is asserted for one cycle (changing value from 1 to 0 and back to 1) after the LTSSM transitions from l2.idle to detect. When this pulse is asserted, the Application Layer should generate an internal reset signal that is asserted for at least 32 cycles.

lane_act[3:0]

Output

Lane Active Mode: This signal indicates the number of lanes that configured during link training. The following encodings are defined:

  • 4’b0001: 1 lane
  • 4’b0010: 2 lanes
  • 4’b0100: 4 lanes
  • 4’b1000: 8 lanes
ltssmstate[4:0]

Output

LTSSM state: The LTSSM state machine encoding defines the following states:

  • 00000: Detect.Quiet
  • 00001: Detect.Active
  • 00010: Polling.Active
  • 00011: Polling.Compliance
  • 00100: Polling.Configuration
  • 00101: Polling.Speed
  • 00110: Config.Linkwidthstart
  • 00111: Config.Linkaccept
  • 01000: Config.Lanenumaccept
  • 01001: Config.Lanenumwait
  • 01010: Config.Complete
  • 01011: Config.Idle
  • 01100: Recovery.Rcvlock
  • 01101: Recovery.Rcvconfig
  • 01110: Recovery.Idle
  • 01111: L0
  • 10000: Disable
  • 10001: Loopback.Entry
  • 10010: Loopback.Active
  • 10011: Loopback.Exit
  • 10100: Hot.Reset
  • 10101: L0s
  • 11001: L2.transmit.Wake
  • 11010: Recovery.Speed
  • 11011: Recovery.Equalization, Phase 0
  • 11100: Recovery.Equalization, Phase 1
  • 11101: Recovery.Equalization, Phase 2
  • 11110: Recovery.Equalization, Phase 3
  • 11111: Recovery.Equalization, Done
rx_par_err

Output

When asserted for a single cycle, indicates that a parity error was detected in a TLP at the input of the RX buffer. This error is logged as an uncorrectable internal error in the VSEC registers. For more information, refer to Uncorrectable Internal Error Status Register. You must reset the Hard IP if this error occurs because parity errors can leave the Hard IP in an unknown state.

The signal is not available for Arria V and Cyclone V devices.

tx_par_err[1:0]

Output

When asserted for a single cycle, indicates a parity error during TX TLP transmission. These errors are logged in the VSEC register. The following encodings are defined:

  • 2’b10: A parity error was detected by the TX Transaction Layer. The TLP is nullified and logged as an uncorrectable internal error in the VSEC registers. For more information, refer to Uncorrectable Internal Error Status Register.
  • 2’b01: Some time later, the parity error is detected by the TX Data Link Layer which drives 2’b01 to indicate the error. Reset the IP core when this error is detected. Contact Intel technical support if resetting becomes unworkable.

Note that not all simulation models assert the Transaction Layer error bit in conjunction with the Data Link Layer error bit.

The signal is not available for Arria V and Cyclone V devices.

Intel does not rigorously test or verify debug signals. Only use debug signals to observe behavior. Do not use debug signals to drive custom logic.

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