1. Overview of the Design Guidelines for Cyclone V SoC FPGAs and Arria V SoC FPGAs
The purpose of this document is to provide a set of design guidelines and
recommendations, as well as a list of factors to consider, for designs that use the
Cyclone® V SoC and Arria V SoC FPGA devices. This
document assists you in the planning and early design phases of the SoC FPGA design,
Platform Designer (Standard) sub-system design, board design and software
Note: This application note
does not include all the
Arria® V Hard Processor System (HPS) device details,
features or information on designing the hardware or software system. For more
information about the
Cyclone® V or
Arria® V HPS features and individual peripherals, refer to
Processor System Technical Reference
Design guidelines for the FPGA portion of your design are provided in the Arria V
and Cyclone V Design Guidelines.
1 You can only assign a maximum
of 71 HPS I/O as Loaner I/O to the FPGA. For a detailed comparison
between the HPS subsystem for
Cyclone® V SoC and
Arria® V SoC, refer
to Differences Among Intel SoC Device
2.1. Guidelines for Interconnecting the HPS and FPGA
The memory-mapped connectivity between the HPS and the FPGA fabric is a
crucial tool to maximize the performance of your design.
Design guidelines for the FPGA portion of your design are provided in
the Arria V and Cyclone V Design Guidelines.
The HPS has three bridges that use memory-mapped interfaces to the FPGA
based on the
Advanced Microcontroller Bus Architecture (
) Advanced eXtensible Interface (
purpose determines the direction of each bridge.
Figure 1. HPS-FPGA Bridges
220.127.116.11. Lightweight HPS-to-FPGA Bridge
GUIDELINE: Use the lightweight HPS-to-FPGA bridge to connect IP that
needs to be controlled by the HPS.
The lightweight HPS-to-FPGA bridge allows masters in the HPS to access
memory-mapped control slave ports in the FPGA portion of the SoC device. Typically, only the
MPU inside the HPS accesses this bridge to perform control and status register accesses to
peripherals in the FPGA.
GUIDELINE: Do not use the lightweight HPS-to-FPGA bridge for FPGA
memory. Instead use the HPS-to-FPGA bridge for memory.
When the MPU accesses control and status registers within peripherals, these
transactions are typically strongly ordered (non-posted). By dedicating the lightweight
HPS-to-FPGA bridge to register accesses, the access time is minimized because bursting
traffic is routed to the HPS-to-FPGA bridge instead.
The lightweight HPS-to-FPGA bridge has a fixed 32-bit width connection to
the FPGA fabric, because most IP cores implement 32-bit control and status registers.
However, Platform Designer (Standard) can adapt the transactions to widths other than 32 bits
within the FPGA-generated network interconnect.
18.104.22.168. HPS-to-FPGA Bridge
GUIDELINE: Use the HPS-to-FPGA bridge to connect memory hosted by the
FPGA to the HPS.
The HPS-to-FPGA bridge allows masters in the HPS such as the microprocessor
unit (MPU), DMA, or peripherals with integrated masters to access memory hosted by the FPGA
portion of the SoC device. This bridge supports 32, 64, and 128-bit datapaths, allowing the
width to be tuned to the largest slave data width in the FPGA fabric connected to the
bridge. This bridge is intended to be used by masters performing bursting transfers and
should not be used for accessing peripheral registers in the FPGA fabric. Control and status
register accesses should be sent to the lightweight HPS-to-FPGA bridge instead.
GUIDELINE: If memory connected to the HPS-to-FPGA bridge is used for HPS
boot, ensure that its slave address is set to 0x0 in Platform Designer (Standard).
When the HPS BSEL pins are set to boot from FPGA (BSEL = 1) the processor
executes code hosted by the FPGA residing at offset 0x0 from the HPS-to-FPGA bridge. This is
the only bridge that can be used for hosting code at boot time.
22.214.171.124. FPGA-to-HPS Bridge
GUIDELINE: Use the FPGA-to-HPS bridge for cacheable accesses to the HPS
from masters in the FPGA.
The FPGA-to-HPS bridge allows masters implemented in the FPGA fabric to
access memory and peripherals inside the HPS. This bridge supports 32, 64, and 128-bit
datapaths so that you can adjust it to be as wide as the widest master implemented in the
GUIDELINE: Use the FPGA-to-HPS bridge to access cache-coherent memory,
peripherals, or on-chip RAM in the HPS from masters in the FPGA.
Although this bridge has direct connectivity to the SDRAM subsystem, the
main intent of the bridge is to provide access to peripherals and on-chip memory, as well as
provide cache coherency with connectivity to the MPU accelerator coherency port (ACP).
To access the HPS SDRAM directly without coherency you should connect
masters in the FPGA to the FPGA-to-SDRAM ports instead, because they provide much more
bandwidth and lower-latency access.
2.1.2. FPGA-to-HPS SDRAM Access
In addition to the FPGA-to-HPS bridge, FPGA logic can also use the
FPGA-to-SDRAM interface to access the HPS SDRAM.
GUIDELINE: Use the FPGA-to-SDRAM ports for non-cacheable access to the HPS SDRAM
from masters in the FPGA.
The FPGA-to-SDRAM ports allow masters implemented in the FPGA fabric to directly access
HPS SDRAM without the transactions flowing through the L3 interconnect.
These interfaces connect only to the HPS SDRAM subsystem so it is recommended to use
them in your design if the FPGA needs high-throughput, low-latency access to the HPS
SDRAM. The exception to this recommendation is if the FPGA requires cache coherent
access to SDRAM.
The FPGA-to-SDRAM interfaces cannot access the MPU ACP slave; so if you require a master
implemented in the FPGA to access cache coherent data, ensure that it is connected to
the FPGA-to-HPS bridge instead.
The FPGA-to-SDRAM interface has three port types that are used to
and Avalon-MM interfaces:
Command ports—issue read as well as write commands, and for
receive write acknowledge responses
64-bit read data ports—receive data returned from a memory
64-bit write data ports—transmit write data
There is a maximum of six command ports, four 64-bit read data port and
four 64-bit write data port. The table below shows the possible port utilization.
Table 5. FPGA-to-HPS SDRAM Port Utilization
Read Data Ports
Write Data Ports
32‑ or 64‑bit
32‑ or 64‑bit Avalon-MM
32‑ or 64‑bit Avalon-MM write‑only
128‑bit Avalon-MM write‑only
256‑bit Avalon-MM write‑only
32‑ or 64‑bit Avalon-MM read‑only
128‑bit Avalon-MM read‑only
256‑bit Avalon-MM read‑only
For more information about the FPGA-to-HPS SDRAM interface, refer to
the "SDRAM Controller Subsystem" chapter of the Cyclone V
or Arria V SoC Hard Processor System Technical Reference
Designers can connect soft logic components to the HPS using the
Arria® V HPS
component in Platform Designer (Standard).
Note: Refer to the
chapters of the
Hard Processor System Technical Reference
to understand the interface and available options. To connect a FPGA soft IP
component to the HPS, Platform Designer (Standard) provides the component
editor tool. For more information, refer to the
"Creating Platform Designer (Standard) Components" chapter of the
Quartus® Prime Standard Edition
Handbook, Volume 1: Design and
Note: When designing and
configuring high bandwidth DMA masters and related buffering in the FPGA core, refer
to the DMA Considerations section of this document.
The principles covered in that section apply to all high bandwidth DMA masters (for
example Platform Designer (Standard) DMA Controller components,
integrated DMA controllers in custom peripherals) and related buffering in the FPGA
core that access HPS resources (for example HPS SDRAM) through the FPGA-to-SDRAM and
FPGA-to-HPS bridge ports, not just tightly coupled
3.1.1. Recommended Starting Point for HPS-to-FPGA Interface Design
Depending on your topology, you can choose one of the two hardware
reference designs as a starting point for your hardware design.
the Golden System Reference Design (GSRD) as a starting point for a loosely coupled
Golden Hardware Reference Design (GHRD) has the optimum default settings and timing that
you can use as a basis for your "getting started" system. After initial evaluation, you
can move on to the
Cyclone® V HPS-to-FPGA Bridge Design
Example reference design to compare performance among the various FPGA-HPS
Refer to "Golden Hardware Reference Design" for more information.
Cyclone® V HPS-to-FPGA Bridge Design Example
reference design to determine your optimum burst length and data-width for accesses
between FPGA logic and HPS.
These pins are also known as HLGPI pins. These
input-only pins are located in the same bank as the HPS EMIF I/O. Note that
the smallest Cyclone V SoC package U19 (484 pins) does not have any HPS GPI
These are general purpose I/O that can be used for
FPGA logic and FPGA External Memory Interfaces.
The table below summarizes the characteristics of each I/O type.
Table 7. I/O Types
HPS Dedicated Function Pins
HPS Dedicated I/O with loaner capability
HPS External Memory Interface
HPS General Purpose Input
Number of Available I/O
Up to 67 (
SoC) and 94 (
Arria® V SoC)
Up to 86
14 (except for
Cyclone® V SoC U19 package )
Up to 288 (
Cyclone® V SoC) and Up to 592 (
Because the HPS contains more peripherals than can all be connected to
the HPS Dedicated I/O, the HPS component in Platform Designer (Standard)
offers pin multiplexing settings as well as the option to route most of the peripherals
into the FPGA fabric. Any unused pins for the HPS Dedicated I/O with loaner capability
meanwhile can be used as general purpose I/O by the FPGA.
Note that a HPS I/O Bank can only support a single supply of either 1.2V,
1.35V, 1.5V, 1.8V, 2.5V, 3.0V, or 3.3V power supply, depending on the I/O standard
required by the specified bank. 1.35V is supported for HPS Row I/O bank only.
GUIDELINE: Ensure that you route USB, EMAC and Flash interfaces to
HPS Dedicated I/O first, starting with USB.
It is recommended that you start by routing high speed interfaces such as
USB, Ethernet, and flash to the HPS Dedicated I/O first. USB
be routed to HPS Dedicated I/O because it is not available to the FPGA fabric. The flash
boot source must also be routed to the HPS dedicated I/O (and not any FPGA I/O)
these are the only
that are functional before the FPGA
have been configured.
GUIDELINE: Enable the HPS GPI pins in the Platform Designer (Standard) HPS Component if needed
By default, the HPS GPI interface is not enabled in Platform Designer (Standard). To enable this interface, you must select the
checkbox "Enable HLGPI interface" in the Platform Designer (Standard) HPS
Arria® V. These pins are then exposed as part of the Platform Designer (Standard) HPS Component Conduit Interface and can be individually assigned at
the top level of the design.
3.2.2. HPS I/O Settings: Constraints and Drive Strengths
GUIDELINE: Ensure that you have I/O settings for the HPS Dedicated I/O (drive
strength, I/O standard, weak pull-up enable, etc.)
The HPS pin location assignments are managed automatically when you
generate the Platform Designer (Standard) system containing the HPS. As for
the HPS SDRAM, the I/O standard and termination settings are done once you run the
“hps_sdram_p0_pin_assignments.tcl” script that
is created once the Platform Designer (Standard) HPS Component has been
Note: You can locate the
script “hps_sdram_p0_pin_assignments.tcl” in the
following directory once the Platform Designer (Standard) HPS Component
has been generated: <Quartus project
directory>\<Platform Designer (Standard) file
name>\synthesis\submodule. Shown below is an example of selecting
the script in
The only HPS I/O constraints you must manage are for HPS Dedicated
Function Pins and HPS Dedicated I/O. Constraints such as drive strength, I/O standards,
and weak pull-up enables are added to the
Quartus® Prime project just like
FPGA constraints and are applied to the HPS at boot time when the second stage
bootloader configures the I/O. For FPGA I/O, the I/O constraints are applied to the FPGA
Note: During power up, the HPS Dedicated I/O required for boot flash devices are
configured by the Boot ROM, depending on the BSEL values.
3.3. HPS Clocking and Reset Design Considerations
The main clock and resets for the HPS subsystem are HPS_CLK1, HPS_CLK2, HPS_nPOR, HPS_nRST and HPS_PORSEL.
HPS_CLK1 sources the Main PLL that generates the clocks
for the MPU, L3/L4 sub-systems, debug sub-system and the Flash controllers. It can also be
programmed to drive the Peripheral and SDRAM PLLs. HPS_CLK2 meanwhile can be used as an alternative clock source to the
Peripheral and the SDRAM PLLs.
HPS_nPOR provides a cold reset input, and
HPS_nRST provides a bidirectional warm reset resource.
As for the HPS_PORSEL, it is an input pin that can be used
to select either a standard POR delay or a fast POR delay for the HPS block.
GUIDELINE: Verify MPU and peripheral clocking using
Platform Designer (Standard)
Platform Designer (Standard) to initially define your HPS
component configuration. Set the HPS input clocks, and peripheral source clocks and
frequencies. Note any
Platform Designer (Standard) warning or error messages.
can address them by modifying clock
settings. In some
cases you might determine
a particular warning
3.3.2. Early Pin Planning and I/O Assignment Analysis
GUIDELINE: Choose an I/O voltage level for the HPS Dedicated Function I/O
HPS_CLK1, HPS_CLK2, HPS_nPOR and HPS_nRST are powered by
VCCRSTCLK_HPS. These HPS Dedicated Function Pins are
LVCMOS/LVTTL at either 3.3V, 3.0V, 2.5V or 1.8V. The I/O signaling
voltage for these pins are determined by the supply level applied to
Note:HPS_PORSEL can be connected to either
VCCRSTCLK_HPS (for fast HPS POR delay) or GND
(for standard HPS POR delay).
Note:VCCRSTCLK_HPS can share the same power and regulator with
VCCIO_HPS and VCCPD_HPS if they share the same voltage requirement. The functionality
of powering down the FPGA fabric, while keeping the HPS running, is not
3.3.3. Pin Features and Connections for HPS JTAG, Clocks, Reset and PoR
GUIDELINE: With the HPS in use (powered), supply a free running
clock on HPS_CLK1 for SoC device HPS JTAG
Access to the HPS JTAG requires an active clock source driving HPS_CLK1.
GUIDELINE: When daisy chaining the FPGA and HPS JTAG for a single
device, ensure that the HPS JTAG is first device in the chain (located before the FPGA
Placing the HPS JTAG before the FPGA JTAG allows the ARM DS-5 debugger
to initiate warm reset to the HPS. However, in case of cold reset the entire JTAG chain
is broken until the cold reset completes, as discussed in the next section.
GUIDELINE: Consider board design to isolate HPS JTAG
The HPS Test Access Port (TAP) controller is reset on a cold reset. If
the HPS JTAG and FPGA JTAG are daisy-chained together, the entire JTAG chain is broken
until the cold reset completes.
access to the JTAG chain is required during HPS cold reset, design the
JTAG to be
GUIDELINE: HPS_nRST is an
open-drain, bidirectional dedicated warm reset I/O.
HPS_nRST is an active low,
open-drain-type, bidirectional I/O. Externally asserting a logic low to the HPS_nRST pin initiates a warm reset of the HPS subsystem.
HPS warm and cold reset can also be asserted from internal sources such as
software-initiated resets and reset requests from the FPGA fabric. When the HPS is
internally placed in a warm reset state, the HPS component becomes a reset source and
drives the HPS_nRST pin low, resetting any connected
GUIDELINE: Observe the minimum assertion time specifications of
HPS_nPOR and HPS_nRST.
GUIDELINE: Avoid cascading PLLs between the HPS and FPGA
Cascading PLLs between the FPGA and HPS has not been characterized. Unless you perform
the jitter analysis, do not chain the FPGA and HPS PLLs together as a stable clock
coming out of the last PLL in the FPGA cannot be guaranteed. Output clocks from the HPS
are not intended to be fed into PLLs in the FPGA.
3.4. HPS EMIF Design Considerations
A critical component of the HPS subsystem is the external SDRAM memory.
Cyclone® V and
Arria® V SoC device, the HPS has a dedicated SDRAM Subsystem that interfaces with the HPS
External Memory Interface I/O.
interface between the memory and
guidelines are essential to successfully connecting external SDRAM to
GUIDELINE: Ensure that the HPS memory controller Data Mask (DM) pins
In the HPS Component in Platform Designer (Standard), ensure
that the checkbox to enable the data mask pins is enabled. If this control is not
enabled, data corruption
any time a master accesses data in SDRAM that is smaller than the native word size of
Figure 3. Setting the Enable DM
Determine your SDRAM Memory type and bit width.
Cyclone® V and
Arria® V SoC devices offer
DDR3, DDR2 and LPDDR2 SDRAM support for the HPS.
GUIDELINE: Ensure that you choose only DDR3, DDR2, or LPDDR2
components or modules in configurations supported by the
Cyclone® V or
Arria® V HPS EMIF for your
specific device/package combination.
Memory Interface Spec Estimator, available on the External Memory
Interface page, is a parametric tool that allows you to
compare supported external memory interface types, configurations and maximum
performance characteristics in
Intel® FPGA and SoC devices.
First, filter the “Family” to select only
Cyclone® V /
Arria® V SoC device. Then, follow
on by using the filter on “Interface Type” to choose only “HPS Hard Controller”
GUIDELINE: Ensure that in the
Component, the Memory Clock Frequency is supported by the device speed grade.
obtain the maximum supported memory clock frequency for the device speed grade,
Memory Interface Spec Estimator, available on the External Memory Interface
3.4.2. HPS SDRAM I/O Locations
Cyclone® V and
Arria® V SoC HPS External Memory Interface I/O locations are fixed, depending
on the type of memory used. You can refer to the device Pin Out files, under the
“HMC Pin Assignment for DDR3/DDR2” and “HMC Pin Assignment for LPDDR2” for exact I/O pins used by
the respective memory interface pins.
Note: Unused HPS External
Memory Interface I/O Pins cannot be assigned to HPS Peripherals, or used by the FPGA
as Loaner IO.
Note: The smallest
Cyclone® V SoC package U19 (484 pin count) has narrower HPS
SDRAM width (32-bit) compared to larger packages (40-bit). Refer
Cyclone V Device Handbook Volume 1: Device Interfaces and Integration for more information.
3.4.3. Integrating the HPS EMIF with the SoC FPGA Device
Consider the following when integrating the
Arria® V SoC HPS EMIF with the rest of the SoC system
GUIDELINE: Follow the guidelines for optimizing bandwidth for all masters accessing
the HPS SDRAM
Accesses to SDRAM connected to the HPS EMIF go through the L3
Interconnect (except for FPGA-to-SDRAM bridge). When designing and configuring high
bandwidth DMA masters and related buffering in the FPGA core, refer to DMA Considerations. The principles covered in that
section apply to all high bandwidth DMA masters
components, integrated DMA controllers in custom peripherals) and related buffering in
the FPGA core that access HPS resources
example HPS SDRAM) through the FPGA-to-SDRAM and FPGA-to-HPS bridge
ports, not just tightly-coupled HPS hardware accelerators.
3.4.4. HPS Memory Debug
Cyclone® V /
Arria® V HPS EMIF do not support the external memory interface toolkit. To
debug the HPS EMIF, you can change the settings inside the preloader software to enable
Runtime Calibration Report and Debug Level info. In addition, you can use the preloader
software to check the status of HPS SDRAM PLL.
Cyclone® V and
Arria® V HPS EMIF support address mirroring. This feature can be turned
on under the Memory Initialization Options sub-window in the Memory
Parameters tab under the Interface Type sub-window of the DDR3
SDRAM Controller with UniPHY GUI. For example, for four chip selects, enter
1011 to mirror the address on chip select #3, #1,and #0.
For more information about address mirroring, refer to External Memory
Interface Handbook, Volume 1: Introduction and Specifications.
Choose the DMA implementation best suited to your design
When DMA is required to improve system performance, you have the option to use the DMA
integrated into the HPS or a soft DMA module in the FPGA. When making the choice of
which option to use, you should consider the following:
HPS DMA: primarily used to move data to and from other slow-speed
HPS modules, such as SPI and I2C, as well as to do memcopy functions to
and from HPS memories.
Soft DMAs: primarily used to move data to and from peripherals in the FPGA.
3.5.2. Optimizing DMA Master Bandwidth through HPS Interconnect
FPGA DMA masters have access to HPS resources through the FPGA-to-HPS Bridge
and FPGA-to-SDRAM Interface, configurable in the HPS Platform Designer (Standard) Component. The HPS SDRAM controller multi-port-front end (MPFE) provides arbitration for
these resources and enforce Quality of Service (QoS) settings. When planning for and
designing DMA masters and related buffering that access resources through the HPS
interconnect, study the architecture of the HPS interconnect and consider the following
guidance and resources available for optimizing bandwidth through the interconnect.
GUIDELINE: Utilize the
Bridge Design Example to tune for performance
The example design includes a utility that can select the datapaths
between endpoints, select transaction characteristics (for example, burst lengths), and
report transfer bandwidth. This utility runs on the ARM
A-9 processor in the HPS.
3.5.3. Timing Closure for FPGA Accelerators
The HPS bridges and FPGA-to-SDRAM interfaces exposed to the FPGA are
synchronous and clock crossing is performed within the interface itself. As a result,
you only need to ensure that both the FPGA-facing logic and your user design close
Timing Analyzer. Interrupts are considered asynchronous
by the HPS, and as a result the HPS logic resynchronizes them to the internal HPS clock
domain so there is no need to close timing for them.
Conduits carry signals that do not fit into any standard interface supported by Platform Designer (Standard). Examples of these are HPS peripheral external interfaces routed into
the FPGA fabric or the HPS DMA peripheral request interfaces.
3.6. Managing Coherency for FPGA Accelerators
Data shared between the HPS and the FPGA logic can be modified at any
by either the HPS or the FPGA.
data coherency, which means that
so that every master
you design for data coherency, first you must
which data transfers need to be coherent. By default all access between the FPGA and HPS
are assumed to be non-coherent unless coherency is explicitly managed by software or
using coherent hardware features of the HPS (SCU
To determine if peripherals in the FPGA need
access to HPS memory,
the follow questions:
Does the MPU
need to access
generated by my FPGA
Does the FPGA
peripheral need to access
generated by the
the answer to
must be coherent. You can use the ACP to keep the FPGA coherent with cacheable data in
3.6.1. Cache Coherency
There are several mechanisms via which coherency are maintained through
The HPS maintains cache coherency at a level 1 memory subsystem level
within the MPU subsystem. The snoop control unit (SCU) built into the MPU subsystem
maintains cache coherency between the two L1 data caches using the
modified-exclusive-shared-invalid (MESI) coherency protocol.
3.6.2. Coherency between FPGA Logic and HPS: Accelerator Coherency Port (ACP)
The accelerator coherency port (ACP) of the SCU provides a means for
other masters in the system, including logic implemented in the FPGA fabric, to perform
cache coherent accesses. Accesses to the ACP are only unidirectional in terms of cache
coherency meaning at the time of the access the data is up to date, but the SCU is not
responsible for maintaining coherency of that data over time. For example, if a master
in the FPGA reads data from the ACP and then a processor updates that same data in
memory, then the FPGA no longer contains the most up to date copy of the data.
3.6.3. Data Size Impacts ACP Performance
Performance explorations of accelerators using ACP show that as size of
packets transferred by
master via the ACP port increases the accelerator performance
increases but only up to a point. After that
it is no longer possible to cache the entire data
GUIDELINE: Use ACP for managing coherency for small data size accesses, manage
coherency for large data in software.
3.6.4. Avoiding ACP Dependency Lockup
access scenarios can create deadlock through the ACP and the CPU. However, you can avoid this
type of deadlock with a simple access strategy.
In the following
example, the CPU creates deadlock by initiating an access to the HPS through the FPGA
The CPU initiates a device memory access to the FPGA fabric. The CPU pipeline must stall
until this type of access is complete.
Before the FPGA fabric state machine can respond to the device memory access, it must
access the HPS coherently. It initiates a coherent access, which requires the ACP.
The ACP must perform a cache maintenance operation before it can complete the access.
However, the CPU’s pipeline stall prevents it from performing the cache maintenance
operation. The system deadlocks.
You can implement the desired access without deadlock, by breaking it into smaller pieces.
For example, you can initiate the operation with one access, then determine the operation
status with a second access.
3.6.5. FPGA Access to ACP via AXI or Avalon-MM
protocol allows masters to issue cacheable accesses whereas the
Avalon-MM protocol does not support this feature. For an FPGA master to perform a
cacheable access, the master must adhere to the
protocol and be able to perform
cacheable accesses, with ARCACHE or AWCACHE set to 1 and
ARUSER or AWUSER set to 1.
3.6.6. Data Alignment for ACP and L2 Cache ECC accesses
The L2 cache performs error detection and correction in groups of 64 bits
without the use of byte enables.
to the ACP must be 64-bit
byte lanes can
The main L3 switch and the ACP port are both 64 bits wide, so it is only necessary to
provide 64-bit aligned cache coherent accesses that are 64 bits wide after resizing.
Data resizing can occur in the L3 interconnect between requesting master
and the ACP. As a result, a 32-bit access can be compatible with the L2 cache ECC logic
if the access is aligned to 8-byte boundaries and the master performs bursts of size 2,
4, 8, or 16. Data resizing can also occur within the FPGA-to-HPS bridge.
GUIDELINE: The simplest way to ensure that accesses from the FPGA
the L2 cache ECC requirements is to implement 64-bit masters in the FPGA fabric and
configure the FPGA-to-HPS bridge to expose a 64-bit slave port. This
that no resizing of
necessary. Full 64-bit accesses have to be made by the logic in the FPGA as
3.7. IP Debug Tools
Quartus® Prime Design Software
many IP and system-level debug tools used in FPGA hardware designs.
The following tools are commonly used for system and IP debug in embedded
On-chip logic analyzer constructed from FPGA resources
Bus functional models
Avalon-MM v2 protocol
console - Services-based API for controlling soft logic and moving data to/from
Each debug tool is introduced at different stages of the hardware design.
In a typical hardware design flow, the developer follows these
IP Creation in RTL
Testbench and BFM verification of the IP
In silicon testing of the IP using system console to drive
stimuli into memory-mapped or streaming interface
In silicon testing of the IP using low level software run on the
processor in the HPS
In the case of Signal Tap and system console, if both
use the FPGA JTAG interface to communicate data then they can be used simultaneously.
For example, you may instrument a trigger condition in Signal Tap and
cause the trigger condition to occur via the JTAG-to-Avalon bridge IP controlled by
System console. These tools are also capable of being used simultaneously with the HPS
tools that communicate over JTAG.
There are two JTAG interfaces on the
Arria® V SoC device. The first
interface is connected to the FPGA side of the device, while the second interface is
connected to the HPS debug access port (DAP).
This section describes the considerations that are useful for board bring up.
4.1.1. Reserved BSEL Setting
During initial stages of
if a JTAG connection cannot be established to the target, it may be beneficial to set
BSEL to 0x0 “Reserved” setting to prevent the BootROM from trying to boot from a
specific boot source. Then a test program could be downloaded and ran with a
4.2. Boot and Configuration Design Considerations
4.2.1. Boot Design Considerations
126.96.36.199. Boot Source
GUIDELINE: Determine which boot source is to be supported.
The HPS side of the
Cyclone® V SoC /
Arria® V SoC can be booted from a variety of
sources, as selected by the BSEL pins:
Each possible boot source has its own strengths:
SD cards are cheap, universally available, and have large storage
capacities. Industrial versions available, with improved reliability. They are
managed NAND flash, so wear leveling and bad block management are performed
eMMC devices have smaller packages, are available in large
capacities, and can be more reliable than SD. They are not removable, with can be
a plus, allowing a more rugged operation.
QSPI devices are very reliable, typically with a minimum 100,000
cycles of erase cycles per sector.
the other options. They are typically used as a boot source, but not as an
NAND devices are available in large sizes, but they are unmanaged
NAND, which means that techniques such as wear leveling and bad block management
need to be implemented in software.
FPGA boot allows HPS to boot without the need of an external
Flash device. The FPGA boot memory can be synthesized our of FPGA resources
(typically pre-initialized embedded memory blocks) or can be memory connected to
the FPGA such as an external SRAM or SDRAM.
boot from FPGA, the FPGA must be configured using a traditional configuration
188.8.131.52. Select Desired Flash Device
GUIDELINE: Select the boot flash device.
When choosing a flash device to incorporate with SoC FPGA devices, it is
important to consider the following:
the flash device
with the HPS
ROM ?: The HPS can only boot from flash devices supported
Is the device verified to work and supported
by software like Preloader, U-Boot and Linux ?: For supported devices,
Intel® provides the Preloader, U-Boot and Linux
software. For other devices, this software must be developed by the user.
Is the flash device supported by the HPS Flash
Programmer?: The HPS Flash Programmer enables writing to flash using a JTAG
connection, primarily to program the initial pre-loader/bootloader image. If the
device is not supported by the HPS Programmer, other flash programming methods may
be used, such as using the HPS to program flash. For example, the flash
programming capabilities of U-Boot can be used.
GUIDELINE: Configure the BSEL pins for the selected boot source.
The boot source is selected by means of BSEL pins.
It may be beneficial to change the boot source for debugging purposes,
even if the board does not have available another boot source. For
on a board booting from QSPI it may be beneficial to select the reserved boot so that
BootROM would not do anything. Or select boot from FPGA and put a test image in the FPGA
If the system allows it (space constraints etc.) plan to provide either switches or at
least resistors to be able to change BSEL as needed.
184.108.40.206. Boot Clock
GUIDELINE: Determine boot clock source.
influences the boot duration.
Consider your system
boot speed requirement as the primary factor in choosing the book clock.
boot time requirement
on how fast the FPGA needs to be
configured for an
appropriate response time,
the HPS software must be booted. The HPS software boot speed is
influenced by the following factors:
Value of external clock to the HPS (i.e. OSC1 clock)
Boot flash source interface operation frequency
are selected with
the CSEL pins. Available combinations are described in the appropriate
System Technical Reference
pins are not used when booting from FPGA fabric.
GUIDELINE: Provide a method to configure CSEL options.
For debugging purposes, it may be beneficial to allow setting of various
CSEL values even if the end product requires just one CSEL setting. If possible, design
the board in such a way that the CSEL configuration can be varied even if a single value
can be used eventually. This configurability may be useful for debugging and could be
done by resistors, jumpers or switches.
220.127.116.11. Selecting NAND Flash Devices
GUIDELINE: Select a NAND flash that is ONFI 1.0 compliant.
When booting from NAND, ensure that the selected device is ONFI 1.0
The NAND device used for booting must also have a
interface, and only a single pair of ce# and rb# pins.
Although some non-ONFI 1.0 compliant devices are compatible with the
BootROM, the HPS Flash Programmer only supports ONFI compliant devices.
18.104.22.168. Determine Flash Programming Method
GUIDELINE: Ensure that the board is configured properly to support
The HPS Flash Programmer is a tool provided with SoC EDS that can be used
to program QSPI and NAND flash devices on
Cyclone® V /
Arria® V SoC boards. The tool is intended to write
relatively small amounts of data (for example the preloader) since it works over JTAG
and has a limited speed.
22.214.171.124. For QSPI and SD/MMC/eMMC Provide Flash Memory Reset
GUIDELINE: Ensure that the QSPI and SD/MMC/eMMC devices have a mechanism to be
reset when the HPS is reset.
The QSPI and SD/MMC/eMMC flash devices can potentially be put in a state by software
where the BootROM cannot access them successfully, which may trigger a boot failure on
the next reset. This problem can occur because the HPS is reset, but the flash part is
It is therefore required to reset the QSPI and SD/MMC/eMMC boot flash devices each time
there is an HPS reset (warm or cold).
Note that some devices do not have a reset pin. In such a case, you must
power-cycle the flash by other means, for example with a MOSFET. Pay attention to
minimum required reset pulse duration.
126.96.36.199. Selecting QSPI Flash Devices
GUIDELINE: For bare-metal applications, avoid using a QSPI flash device
larger than 16 MB
QSPI flash devices of 16 MB or less always support three-byte addressing.
Therefore, they are accessible to the HPS Boot ROM. With such devices, you do not need to
reset or power-cycle the flash when the HPS undergoes cold or warm reset.
GUIDELINE: With a QSPI device larger than 16 MB, use QSPI extended
4-byte addressing commands if supported by the device
Some QSPI flash devices support an extended command set, allowing the
master to use four-byte addressing without switching to four-byte addressing mode. If you
use the extended command set, you can leave the flash device in three-byte addressing mode,
so that the Boot ROM can access it on the next reset cycle without resetting or
power-cycling the flash device.
Cyclone® V /
Arria® V SoC devices support two main type sof configuration flows:
Traditional FPGA configuration
HPS-initiated FPGA configuration
HPS-initiated configuration uses fast passive parallel (FPP) mode
allowing the HPS to configure the FPGA using storage locations accessible to the HPS
such as QSPI, SD/MMC and NAND flash. The FPGA configuration flows for the
Arria® V SoC are the same for the
Arria® V FPGA devices where
an external configuration data source is connected to the control block in the FPGA.
188.8.131.52. Traditional Configuration
The traditional FPGA configuration flow is where the FPGA is configured by an external
source such as JTAG, active serial or fast passive parallel.
184.108.40.206. HPS Initiated Configuration
When the device is powered and the HPS begin executing the software in the boot ROM, all
the device I/O default to an input tri-state mode of operation. The boot ROM configures
the dedicated boot I/O based on the sampled BSEL pins.
4.2.3. Reference Materials
Refer to the following reference materials for additional information.
For design considerations and recommendations on power consumption and
thermal analysis, SoC device pin connections, supply design and decoupling, refer to the
Arria® V and
The following sections are supplemental for SoC devices.
Follow the guidelines in the Early Power
Estimation website for using the
Quartus® Prime software power
In addition, consider the following guidelines for
Cyclone® V and
Arria® V SoC
devices when using the EPE spreadsheet.
GUIDELINE: Use the Main worksheet to select “Maximum” for the Power
When estimating power consumption for the purposes of designing an
adequate power supply that can meet the maximum power requirements across process,
voltage and temperature (PVT), use the device maximum power characteristics.
GUIDELINE: Use the I/O worksheet to add HPS peripherals assigned to
This tab is where you describe the various configurations of I/O
Elements (IOEs) in your application. Use the IO-IP tab to describe the controller IP
behind each set of I/O.
For HPS peripherals assigned to FPGA I/O, add rows to the spreadsheet as
necessary to describe the different HPS peripheral I/O characteristics in your design.
GUIDELINE: Use the HPS worksheet to select the Frequency,
Application, and if applicable, the Application Mode for each CPU.
The Application/Application Mode settings for each CPU allow you to
select from a list of industry standard benchmarks to model CPU utilization in your
application. You can also select “Custom” for defining a unique set of CPU utilization
parameters across the ALUs and cache memories.
GUIDELINE: Use the HPS worksheet to update the HPS SDRAM Type,
Frequency and Width.
Note that the selection of SDRAM type also updates the I/O voltage for
Bank 6A to 6B.
GUIDELINE: Use the HPS worksheet to update the HPS I/O Bank Voltage
and Peripheral Usage
Before you select Peripheral voltage from the drop-down list, ensure
that you have at least one HPS I/O Bank that is configured to the same voltage.
Cyclone® V SoC with L
power option, apply the appropriate multiplication factor when calculating the total
There is no L-power option in the EPE for
Cyclone® V, hence you need to calculate the total static power using the
Key in the design and resource utilization using the standard
(non-L) part number.
Once total static power is obtained, apply a multiplication
factor of 0.7 (for 25K-LE and 40K-LE devices) or 0.8 (for 85K-LE and 110K-LE
devices) to calculate the lower static power for the L-power option devices.
Note: The multiplication factor only
applies to total static power and not dynamic power.
4.3.2. Design Considerations for HPS and FPGA Power Supplies for SoC FPGA devices
220.127.116.11. Consider the Need to Power Down the FPGA Portion While Keeping the HPS Running
GUIDELINE: Use a separate programmable regulator for FPGA supply
down the FPGA while keeping the HPS running.
Arria® V SoC devices offer the ability to power down the FPGA while keeping
the HPS running.
do this, the FPGA
must be sourced from a programmable regulator that supports a control interface such as
Cyclone® V SoC Development Kit
an example of a development board that supports this feature.
You can find
information about the
Cyclone® V SoC Development Kit at
Cyclone® V SoC
Development Kit and Intel® SoC FPGA Embedded
18.104.22.168. Consider Desired HPS Boot Clock Frequency
Cyclone® V /
Arria® V SoC devices support a HPS boot clock from 10-50 MHz in PLL bypass
mode, and up to 400MHz in PLL Locked mode. During power up or cold reset, the boot ROM
samples the value of the CSEL pins and if needed,
configure the HPS PLL to provide a faster boot clock frequency.
Refer to the table with CSEL
in the "Booting and
appendix of the appropriate
System Technical Reference
4.3.3. Pin Connection Considerations for Board Designs
22.214.171.124. Device Power-Up
Power-Up and Power-Down Sequencing
Arria® V SoC devices have the following additional power rails to consider
for power sequencing.
the "Power Management" chapter
Volume 1: Device Interfaces and Integration
Arria® V Device
GUIDELINE: Consider ramp times for maximum transient currents on
supplies when designing the Power Distribution Network (PDN).
When using the PDN Tool to calculate the required target impedance of
your application’s PDN for the core fabric’s VCC
supply, model the ramp time of the maximum transient current on VCC using the Core Clock Frequency and Current Ramp Up Period parameters.
This procedure relaxes the target impedance requirements relative to the default step
function analysis, resulting in a more efficient PDN with fewer decoupling
Initial transient current estimates can be obtained from the EPE
Spreadsheet, and more accurate analysis is possible with the Power Analyzer Power
Analysis Tool in
Quartus® Prime when your design is closer to
The biggest contribution to power consumption from the HPS is the
processor clock speed and the type, size and speed of the external SDRAM program memory.
Careful selection of these system parameters to satisfy the functional and performance
requirements of the application helps to minimize system power consumption.
Standby Modes and Dynamic Clock Gating
CPU standby modes and dynamic clock gating logic can be utilized
throughout the MPU subsystem. Each CPU can be placed in standby mode, Wait for
Interrupt, or Wait for Event mode to further minimize power consumption.
When configuring the HPS component in
Platform Designer (Standard), enable only those peripherals your
Configure the peripherals for the lowest clock speed while maintaining functional and
performance requirements. Additional power can be saved under software control by
placing inactive peripherals in reset and gating off their clock sources.
Managing Power by Shutting Down Supplies
Cyclone® V SoC and
Arria® V SoC support the ability to power down the FPGA
portion of the device, while keeping the HPS running. Refer to the
Cyclone® V SoC Smart
design example on how to control the FPGA power supply regulator using the I2C connection from the HPS.
4.4. Boundary Scan for HPS
GUIDELINE: Ensure that the HPS is powered up and held in reset before performing a
boundary scan test of the FPGA and HPS I/O.
The HPS JTAG does not support boundary scan tests (BST). To perform
boundary scan testing on HPS I/O pins, you must use the FPGA JTAG.
4.5. Design Guidelines for HPS Interfaces
This section outlines the design guidelines for HPS Interfaces like EMAC PHY, USB, QSPI,
SD/MMC, NAND Flash, UART, I2C and SPI.
4.5.1. HPS EMAC PHY Interfaces
When configuring an HPS component for EMAC peripherals within Platform Designer (Standard), you must select from one of the following supported
PHY interfaces for each EMAC instance:
Reduced Gigabit Media Independent Interface (RGMII) using
Media Independent Interface (MII) interface to FPGA fabric
Gigabit Media Independent Interface (GMII) interface to FPGA
Any combination of supported PHY interface types can be configured across
multiple HPS EMAC instances.
GUIDELINE: For RGMII using HPS Dedicated I/O, develop an early I/O
floor-planning template design to ensure that there are enough HPS Dedicated I/O to
accommodate the chosen PHY interfaces in addition to other HPS peripherals planned for
HPS Dedicated I/O usage.
Note: For guidelines on configuring
the HPS component, refer to the "Introduction to the HPS Component" chapter of the
Arria® V Hard Processor System
Technical Reference Manual.
It is possible to adapt the MII/GMII PHY interfaces exposed to the FPGA
fabric by the HPS component to other PHY interface standards—such as RMII, RGMII, SGMII,
MII and GMII—by using soft adaptation logic in the FPGA and features in the
general-purpose FPGA I/O and transceiver FPGA I/O.
GUIDELINE: When selecting a PHY device, consider the desired
Ethernet rate, available I/O and available transceivers; PHY devices that offer the skew
control feature; and device driver availability.
Note: Refer to the device drivers
available for your OS of choice or the Linux device driver provided with the
Arria® V SoC
development kit (Golden System Reference Design)
Arria® V SoC Hard Processor System (HPS) can connect its embedded Ethernet
MAC (EMAC) PHY interfaces directly to industry standard Gigabit Ethernet PHYs using the
RGMII interface at any supported I/O voltage using the HPS Dedicated I/O pins. These
voltages typically include 1.8V, 2.5V and 3.0V. If the HPS Dedicated I/O pins are used
for the PHY interface, then no FPGA routing resources are used and timing is fixed,
simplifying timing on the interface. This document describes the design guidelines for
RGMII, the most typical interfaces.
You can also connect PHYs to the HPS EMACs through the FPGA fabric using
the GMII and MII bus interfaces for Gigabit and 10/100 Mbps access respectively. A
GMII-to-SGMII adapter is also available to automatically adapt to transceiver-based
SGMII optical modules.
Note: Due to an erratum in the
SoC device, the RMII PHY interface is not supported when routing through the HPS
Dedicated I/O. RMII interface however is supported when routing through the FPGA
126.96.36.199. PHY Interfaces Connected Through HPS Dedicated I/O
This section discusses design considerations for RGMII PHY interface
through the HPS Dedicated I/O.
Reduced Gigabit Media Independent Interface (RGMII) (Reduced GMII) is the
most common interface as it supports 10 Mbps, 100 Mbps, and 1000 Mbps connection speeds
at the PHY layer. RGMII uses four-bit wide transmit and receive datapaths, each with its
own source synchronous clock. All transmit data and control signals are source
synchronous to TX_CLK, and all receive data and control signals are
source synchronous to RX_CLK.
For all speed modes, TX_CLK is always sourced by the
MAC, and RX_CLK is always sourced by the PHY. In 1000 Mbps mode,
TX_CLK and RX_CLK are 125 MHz, and Dual Data Rate
(DDR) signaling is used. In
10 Mbps and 100 Mbps modes, TX_CLK and
RX_CLK are 2.5 MHz and 25 MHz, respectively, and rising edge Single
Data Rate (SDR) signaling is used.
Figure 5. RGMII
I/O Pin Timing
This section addresses RGMII interface timing from the perspective of
meeting requirements in the 1000 Mbps mode. The interface timing margins are most
demanding in 1000 Mbps mode, thus it is the only scenario we consider here.
At 125 MHz, the period is 8 ns, but because both edges are used, the
effective period is only 4 ns. The TX and RX busses
are completely separate and source synchronous, simplifying timing. The RGMII spec calls
for CLK to be delayed from DATA at the receiver in
either direction by a minimum 1.0 ns and a maximum 2.6 ns.
In other words, the TX_CLK from the MAC to the PHY must
be delayed from the output to the PHY input and the RX_CLK from the PHY
output to the MAC input. The signals are transmitted source synchronously within the
+/-500 ps RGMII skew spec in each direction as measured at the output pins. The minimum
delay needed in each direction is 1ns but it is recommended to target a delay of 1.5 ns
to 2 ns to keep timing margin.
Transmit path setup/hold
Only setup and hold for TX_CLK to
TX_CTL and TXD[3:0] matter for transmit. The
HPS Dedicated I/O does not feature programmable delay.
For TX_CLK from the
Arria® V SoC, you must introduce
the 1.0 ns PHY minimum input setup time in the RGMII spec. It is strongly recommended to
increase this to delay to 1.5 ns to 2.0 ns. Many PHYs offer programmable skew, and some
support RGMII 2.0 which defaults to skew enabled on both transmit and receive
Between PHY delay and FPGA I/O delay features, you must ensure either 2
ns of delay to CLK versus CTL and
D[3:0] or 1.2 ns typical minimum setup skew typical of most PHYs.
Consult the datasheet for your PHY vendor for more details.
GUIDELINE: Ensure your design includes the necessary Quartus settings to configure
the HPS EMAC outputs for the required delays.
Arria® V SoC Development Kit and the associated Golden
Hardware Reference Design (the GHRD is the hardware component of the GSRD) PHY skew is
implemented with the
PHY. Refer to the
file and PHY driver code in the Golden System Reference Design (GSRD).
Receive path setup/hold
Only setup and hold for RX_CLK to
RX_CTL and RXD[3:0] are necessary to consider for
receive timings. For
Arria® V SoC HPS Dedicated I/O no other consideration on the PHY side or
board trace delay is required.
GUIDELINE: Hardware developers should specify the required FPGA skew so that
software developers can add the skew to the device driver code.
used to compile the Linux device tree for the
Cyclone® V or
Arria® V SoC GSRD.
188.8.131.52. PHY Interfaces Connected Through FPGA I/O
Using FPGA I/O for an HPS EMAC PHY interface can be helpful when there is
not enough HPS Dedicated I/O left to accommodate the PHY interface or when you want to
adapt to a PHY interface not natively supported by the HPS EMAC.
GUIDELINE: Specify the PHY interface transmit clock frequency when configuring the
HPS component within Platform Designer (Standard).
For either GMII or MII, including adapting to other PHY interfaces, specify the maximum
transmit path clock frequency for the HPS EMAC PHY interface: 125 MHz for GMII, 25 MHz
for MII. This configuration results in the proper clock timing constraints being applied
to the PHY interface transmit clock upon Platform Designer (Standard) system generation.
MII and GMII are only available in
Arria® V SoC by driving the EMAC signals into the FPGA
core routing logic and then ultimately to FPGA I/O pins or to internal registers in the FPGA
GUIDELINE: Apply timing constraints and verify timing with
Because routing delays can vary widely in the FPGA core and I/O
structures, it is important to read the timing reports, and especially for GMII, create
timing constraints. GMII has a 125 MHz clock and is single data rate unlike RGMII. GMII does
not have the same considerations for CLK-to-DATA skew though; its signals are automatically centered by
design by being launched with the negative edge and captured with the rising edge.
GUIDELINE: Register interface I/O at the FPGA I/O boundary.
With core and I/O delays easily exceeding 8
ns, it is recommended to register these buses in each direction in I/O
Element (IOE) registers, so they remain aligned as they travel across the core FPGA logic
fabric. On the transmit data and control, maintain the clock-to-data/control relationship by
latching these signals on the falling edge of the emac[0,1,2]_gtx_clk output from the HPS EMAC. Latch the receive data and control
at the FPGA I/O inputs on the rising edge of the RX_CLK
sourced by the PHY.
GUIDELINE: Consider transmit timing in MII mode.
MII is 25 MHz when the PHY is in 100 Mbps mode and 2.5 MHz when the PHY is
in 10 Mbps mode, so the shortest period is 40 ns. The PHY sources the clock for both
transmit and receive directions. Because the transmit timing is relative to the TX_CLK clock provided by the PHY, the turnaround time may be of
concern, but this is usually not an issue due to the long
through the FPGA, then out for the
round-trip delay must be less than 25
because there is a
input setup time.
transmit data and control are launched into the FPGA fabric by the HPS EMAC transmit path
logic on the negative edge of the PHY-sourced TX_CLK,
which removes 20 ns of the
clock-to-setup timing budget.
With the round trip clock path delay on the data arrival timing incurring
PHY-to-SoC board propagation delay plus the internal path delay from the SoC pin to and
through the HPS EMAC transmit clock mux taking away from the remaining
setup timing budget, it may be necessary to retime the transmit data and control to the
rising edge of the phy_txclk_o clock output registers in
the FPGA fabric for MII mode transmit data and control.
184.108.40.206.2. Adapting to RGMII
It is possible to adapt the GMII HPS EMAC PHY
signals to an RGMII PHY interface at the FPGA I/O pins using logic in the FPGA. While it is
possible to design custom logic for this adaptation, this section describes using Platform Designer (Standard) adapter IP.
GUIDELINE: Use the GMII-to-RGMII Adapter IP available in Platform Designer (Standard).
Configure the HPS component in Platform Designer (Standard)
for an EMAC as “FPGA” I/O instance. Do not export the resulting HPS component GMII
Platform Designer (Standard). Instead, add the
Intel® HPS GMII to RGMII Converter
to the Platform Designer (Standard) subsystem and connect to the HPS
component’s GMII signals. The
to RGMII Converter
the Intel® HPS EMAC Interface Splitter
in Platform Designer (Standard) to split out the emac conduit from the HPS component for use by the
GMII to RGMII
Converter. See the Embedded Peripherals IP User Guide
for information on how to use the
Intel® HPS GMII to RGMII
GUIDELINE: Provide a glitch-free clock source for the 10/100 Mbps
In an RGMII PHY interface, the TX_CLK
is always sourced by the MAC, but the HPS component’s GMII interface expects TX_CLK to be provided by the PHY device in 10/100 Mbps
modes. The GMII to RGMII adaptation logic must provide the 2.5/25 MHz TX_CLK on the GMII’s emac[0,1]_tx_clk_in input port, and the switch between 2.5 MHz and 25 MHz
must be accomplished in a glitch-free manner as required by the HPS EMAC. An FPGA PLL
can be used to provide the 2.5 MHz and 25 MHz TX_CLK
along with an ALTCLKCTRL block to select between
counter outputs glitch-free.
It is possible to adapt the MII HPS EMAC PHY signals to an RMII PHY interface at the
FPGA I/O pins using logic in the FPGA.
GUIDELINE: Provide a 50MHz REF_CLK
An RMII PHY uses a single 50 MHz reference clock (REF_CLK) for both transmit and receive data and control.
Provide the 50 MHz REF_CLK either with a board-level
clock source, a generated clock from the FPGA fabric, or from a PHY capable of
generating the REF_CLK.
GUIDELINE: Adapt the transmit and receive data and control paths.
The HPS EMAC PHY interface exposed in the FPGA fabric is MII, which requires separate
transmit and receive clock inputs of 2.5 MHz and 25 MHz for 10 Mbps and 100 Mbps modes
of operation, respectively. Both transmit and receive datapaths are 4-bits wide. The
RMII PHY uses the 50 MHz REF_CLK for both its transmit and receive
datapaths and at both 10 Mbps and 100 Mbps modes of operation. The RMII transmit and
receive datapaths are 2-bits wide. At 10 Mbps, transmit and receive data and control are
held stable for 10 clock cycles of the 50 MHz REF_CLK. You must provide
adaptation logic in the FPGA fabric to adapt between the HPS EMAC MII and external RMII
PHY interfaces: 4-bits @ 25 MHz/2.5 MHz to/from 2-bits@ 50 MHz, 10x oversampled in 10
GUIDELINE: Provide a glitch-free clock source on the HPS EMAC MII
tx_clk_in clock input.
The HPS component’s MII interface requires a 2.5/25 MHz transmit clock on its
emac[0,1,2]_tx_clk_in input port, and the switch between 2.5 MHz and
25 MHz must be done glitch free as required by the HPS EMAC. An FPGA PLL can be used to
provide the 2.5 MHz and 25 MHz transmit clock along with an ALTCLKCTRL
block to select between counter outputs glitch-free.
It is possible to adapt the GMII HPS EMAC PHY signals to an SGMII PHY
interface at the FPGA transceiver I/O pins using logic in the FPGA and the multi-gigabit
transceiver I/O. While it is possible to design custom logic for this adaptation, this
section describes using Platform Designer (Standard) adapter IP.
GUIDELINE: Use the
Intel® HPS GMII to TSE 1000BASE-X/SGMII PCS
Bridge, available in Platform Designer (Standard).
Configure the HPS component in Platform Designer (Standard)
for an EMAC as “FPGA” I/O instance. Do not export the resulting HPS component GMII
signals in Platform Designer (Standard). Instead, add the
Intel® HPS GMII to TSE 1000BASE-X/SGMII PCS
Bridge to the Platform Designer (Standard) subsystem and
connect to the HPS component’s GMII signals. The bridge
Intel® HPS EMAC Interface Splitter
in Platform Designer (Standard) to split out the
conduit from the HPS component for use by the GMII
Intel® Triple Speed Ethernet (TSE)
configured in 1000 BASE-X/SGMII PCS PHY-only mode (i.e., no soft MAC component). See the
Peripherals IP User Guide for information on how to use the
Intel® HPS GMII to TSE 1000BASE-X/SGMII PCS
The MDIO PHY management bus has two signals per MAC: MDC and MDIO. MDC is the clock output, which is not free running. At 2.5 MHz,
it has a
minimum period. MDIO is a bi-directional data signal with a
High-Z bus turnaround period.
When the MAC writes to the PHY, the data is launched on the falling edge,
meaning there is 200 ns -10 ns = 190 ns for flight time,
signal settling, and setup at the receiver. Because data is not switched until the following
negative edge, there is also 200 ns of hold time. These requirements are very easy to meet
with almost any board topology. When the MAC reads from the PHY, the PHY is responsible for
outputting the read data from 0 to 300 ns back to the MAC, leaving 100 ns less 10 ns setup
time, or 90 ns for flight time, signal settling, and setup at the receiver. This requirement
is also very easy to meet.
GUIDELINE: Implement pull-up resistor on board for MDC/MDIO.
Both signals require an external pull-up resistor, typically 1K but PHY
data-sheets may vary.
GUIDELINE: Ensure interface timing is met.
There is a 10ns setup and hold requirement for MDIO for data with respect
220.127.116.11. Common PHY Interface Design Considerations
18.104.22.168.1. Signal Integrity
GUIDELINE: Use appropriate board-level termination on PHY outputs.
Not many PHYs offer I/O tuning for their outputs to the
Arria® V SoC, so it is wise to
double check this signal path with a simulator. Place a series resistor on each signal
near the PHY output pins to reduce the reflections if necessary.
GUIDELINE: Minimize reflections at PHY TX_CLK and EMAC RX_CLK inputs to prevent
Be cognizant if the connection is routed as a “T” as signal integrity must be maintained
such that no double-edges are seen at REF_CLK loads. Ensure reflections
at REF_CLK loads are minimized to prevent double-clocking.
GUIDELINE: Use a Signal Integrity (SI) simulation tool.
It is fairly straightforward to run SI simulations on these
unidirectional signals. These signals are almost always point-to-point, so simply
determining an appropriate series resistor to place on each signal is usually enough.
Many times, this resistor is not necessary, but the device drive strength and trace
lengths as well as topology should be studied when making this determination.
4.5.2. USB Interface Design Guidelines
Arria® V SoC Hard Processor system can connect its embedded USB MACs directly
to industry-standard USB 2.0 ULPI PHYs using the HPS Dedicated I/O that support 1.8V,
2.5V, 3.0V and 3.3V I/O standards. No FPGA routing resources are used and timing is
fixed, which simplifies design. This guide describes the design guidelines covering all
supported speeds of PHY operation: High-Speed (HS) 480 Mbps, Full-Speed (FS) 12 Mbps,
and Low-Speed (LS) 1.5 Mbps.
Cyclone® V SoC U19 package (484 pins) only one
USB controller is available.
GUIDELINE: Design the board to support both USB PHY modes where the
device supplies the clock versus where an external clock is the source.
The interface between the ULPI MAC and PHY on the
Arria® V SoC consists of
DATA[7:0], DIR and NXT from the
MAC to the PHY and STP from the MAC to the PHY. Lastly a static clock of 60 MHz is
driven from the PHY and is required for operation, including some register accesses from
the HPS to the USB MAC. Ensure the PHY manufacturer recommendations for
RESET and power-up are followed.
GUIDELINE: Ensure that the USB signal trace lengths are minimized.
At 60 MHz, the period is 16.67 ns and in that time, for example, the clock must travel
from the external PHY to the MAC and then the data and control signals must travel from
the MAC to the PHY. Because there is a round-trip delay, the maximum length of the
CLK and ULPI signals are important. Based on timing
data the maximum length is recommended to be less than 7 inches. This is based on a PHY
with a 5 ns Tco specification. If the specification is slower the total
length must be shortened accordingly.
GUIDELINE: Ensure that signal integrity is considered.
Signal integrity is also important but mostly on the CLK signal driven
from the PHY to the MAC in the HPS subsystem. Because these signals are point-to-point
with a maximum length, they can usually run unterminated but it is recommended to
simulate the traces to make sure the reflections are minimized. Using the 50-ohm output
setting from the FPGA is typically recommended unless the simulations show otherwise. A
similar setting should be used from the PHY vendor if possible.
GUIDELINE: Design properly for OTG
When On-the-Go (OTG) functionality is used, the SoC can become a host or
endpoint. When in host mode consider the power delivery, such as when you are supporting
a USB Flash drive, or potentially a USB Hard Drive. These power requirements and reverse
currents must be accounted for, typically
using external diodes and current limiters such as those used on the
Cyclone® V SoC or
Arria® V SoC development kits.
4.5.3. QSPI Flash Interface Design Guidelines
Up to four QSPI chip selects can be used with
Arria® V SoC. The device can boot
only from QSPI connected to the chip select zero.
GUIDELINE: Ensure that the QSPI_SS
signals are used in numerical order.
Quartus® Prime assumes that the QSPI_SS signals are used in order. It is not possible to use
SS0 and SS2, for
example, without using SS1.
GUIDELINE: If your
design uses QSPI flash with 4-byte addressing, design the board to ensure that the QSPI
flash is reset or power-cycled whenever the HPS is reset.
HPS boot ROM on Cyclone V and Arria V runs in 3-byte address mode by default. If the
QSPI flash is switched to 4-byte addressing during operation, ensure that it is returned
to its default 3-byte addressing mode whenever the HPS is reset. Otherwise, the HPS
boot from or access the QSPI flash memory device.
You can switch
the QSPI to 3-byte addressing mode using one of the following methods:
If the QSPI device has a reset pin, assert the reset signal every
time the HPS device is reset.
If the QSPI device does not have a reset pin, power-cycle the QSPI
device every time the HPS device is reset.
The CV SoC and AV Soc QSPI Boot page of
offers recommendations for implementing the reset signal to the QSPI flash.
QSPI Flash Devices” and
QSPI and SD/MMC/eMMC Provide Flash Memory
4.5.4. SD/MMC and eMMC Card Interface Design Guidelines
GUIDELINE: Include a voltage translator if you plan on support the
SD 1.8V feature. A translator is necessary because the HPS I/O cannot change voltage
levels dynamically like the SD card.
SD cards initially operate at 3.3V, and some cards can switch to 1.8V
after initialization. In addition, some MMC cards can operate at both 1.8V as well as
3.3V. Because the BSEL values are constant during the
boot process, transceivers are required to support level-shifting and isolation for
cards that can operate at 1.8 V.
Follow the guidelines in
Processor System Technical Reference Manual. Some MMC cards
can operate with only 1.8V I/O operation and initial operation at 3.3V is not required.
In this situation, a level shifter is not needed.
Table 8. Level
HPS I/O Bank Voltage
SD Card Voltage
Ensure that timing is considered for initial ID mode and data transfer mode as well as
SD cards initially operate at 400 KHz maximum when they are going
through the ID process. After that there is a data transfer mode, during which the clock
can operate up to 12.5 MHz. In normal operation, the clock can operate up to 50 MHz. The
Boot ROM takes care to ensure that clocking is properly configured during ID and
Refer to the
"CSEL Settings for
table in the
Hard Processor System Technical Reference
GUIDELINE: Ensure that the SD/MMC card is reset whenever the HPS is
To allow the system to boot from SD/MMC, whenever the HPS is reset,
ensure that the SD/MMC card is also reset. This ensures that the memory card is in the
state expected by the boot code.
GUIDELINE: Properly connect flow control signals when routing the UART signals
through the FPGA fabric.
When routing UART signals through the FPGA, the flow control signals are
available. If flow control is not being used, connect the
in the following table.
Table 9. UART
Connections to Disable Flow Control
4.5.7. I2C Interface Design Guidelines
GUIDELINE: Instantiate the open-drain buffer when routing I2C signals
through the FPGA fabric.
When routing I2C signals through the FPGA, note that the
I2C pins from the HPS to the FPGA fabric (i2c*_out_data, i2c*_out_clk) are not
open-drain and are logic level inverted. Thus, when you want to drive a logic level zero
onto the I2C bus, these pins are high. This implementation is
useful as they can be used to tie to an output enable of a tri-state buffer directly.
You must use the altiobuf to implement the open-drain
GUIDELINE: Ensure that the pull-ups are added to the external SDA
and SCL signals in the board design.
Because the I2C signals are open drain, pull-ups are required to make sure
that the bus is pulled high when no device on the bus is pulling it low.
Figure 6. I2C Wiring to FPGA pins
4.5.8. SPI Interface Design Guidelines
GUIDELINE: Consider routing SPI slave signals to FPGA fabric
Due to an erratum in the
Arria® V SoC device, the SPI output enable is not
connected to the SPI HPS pins. As a result, the HPS SPIS_TXD pin cannot be tri-stated by setting the slv_oe bit (bit 10) in the ctrlr0 register to 1.
Routing the SPI Slave signals to FPGA exposes the output enable signal
and allows you to connect it to an FPGA tri-state pin.
GUIDELINE: If your SPI peripheral requires the SPI master slave
select to stay low during the entire transaction period, consider using GPIO as slave
select, or configure the SPI master to assert slave select during the
By default, the SPI master is configured with ctrlr0.scph = 0 and ctrlr0.scpol = 0,
which makes the Cyclone V or Arria V HPS SPI master deassert the slave select signal
between each data word. Set ctrlr0.scph to 1 and
ctrlr0.scpol to 1, to make the SPI master assert
slave select for the entire duration of the transfer.
Alternatively, consider routing the SPI master peripheral to FPGA, and
using GPIO to control the slave select signal.
Note: If you use this method, refer to the following Knowledge Base
5. Embedded Software Design Guidelines for SoC FPGAs
5.1. Embedded Software for HPS: Design Guidelines
5.1.1. Assembling the Components of Your Software Development Platform
To successfully build your software development platform,
that you start with a baseline
a known good configuration of an HPS
Then modify the baseline project to suit your end application.
The following diagram presents the recommended procedure to
determine the software development platform components.
Figure 7. Assembling Software Development Platform
summary, the process consists of following steps:
Select the desired device
as a hardware project starting point
Select the operating system: bare metal, Linux* or partner real-time operating system (RTOS)
Write or update end applications as well as drivers
22.214.171.124. Golden Hardware Reference Design
Hardware Reference Design
Quartus® Prime project that contains a full HPS design for
Cyclone® V SoC /
Arria® V SoC Development Kit. The GHRD has connections to a boot source,
SDRAM memory and other peripherals on the development board.
For every new released version of SoC EDS, the GHRD is included in the
SoC EDS tools. The GHRD is regression tested with every major release of the
Quartus® Prime Design Software and includes the
latest bug fixes for known hardware issues. The GHRD serves as a known good
configuration of an SoC FPGA hardware system.
Cyclone® V /
Arria® V SoC Golden Hardware Reference Design
The GHRD has a minimal set of peripherals in the FPGA fabric, because
the HPS provides a substantial selection of peripherals. HPS-to-FPGA and FPGA-to-HPS
interfaces are configured to a 64-bit data width.
that you use the latest GHRD as a baseline for new SoC FPGA hardware projects. You may
then modify the design to suit your application ends.
<SoC EDS installation
directory>\examples\hardware\cv_soc_devkit_ghrd - for the version
supported by the corresponding SoC EDS version, used as a basis for the provided
5.1.2. Selecting an Operating System for Your Application
126.96.36.199. Linux or RTOS
There are a number of operating systems that support the
Cyclone® V SoC
Arria® V SoC, including Linux
several real-time operating systems (RTOSs). For more information on
Intel®’s SoC Partner OS ecosystem, visit
tab of the
Partner OS providers offer board support packages and commercial support
for the SoC FPGA devices. The Linux community also offers board support packages and
community support for the SoC FPGA device.
There are many factors that go into the selection of an operation system
for SoC FPGAs including the features of the operating system, licensing terms,
collaborative software projects and framework based on the OS, available device drivers
and reference software, in-house legacy code and familiarity with the OS,
requirements of your system, functional safety and other certifications required for
To select an appropriate OS for your application, it is recommended that
you familiarize yourself with the features and support services offered by the
commercial and open source operating systems available for the SoC FPGA.
Intel®’s OS partners, industry websites are a good source
of information you can use to help make your selection.
There are a number of misconceptions when it comes to
performance of operating systems versus bare metal applications. For a Cortex A-class of
processor there are a number of features that
operating systems provide that make efficient use of the processor’s resources in
addition to the facilities provided to manage the run-time application. You may find
that these efficiencies result in sufficient
performance for your application, enabling you to inherit a large body of available
device drivers, middleware packages, software applications and support services. It is
important to take this account when selecting an operating system.
188.8.131.52. Bare Metal
The HPS can be used in a bare-metal configuration (without an OS) and
Intel® offers the
(Hardware Libraries) that consist of both high-level APIs, and
macros for most of the HPS peripherals.
However, to use a bare metal application for the HPS, you must be
familiar with developing run time capabilities to ensure that your bare metal
application makes efficient use of resources available in your
A typical bare-metal application uses only a single core, you must
develop run time capabilities to manage process between both cores and the cache
subsystem if you want to fully utilize the
As your application increases in complexity you may need to build capabilities to
manage and schedule processes, handle inter-process communication and synchronize
between events within your application.
lightweight RTOS offers simple scheduling, inter-process communication and interrupt
handling capabilities that
efficient use of the resources in
184.108.40.206. Using Symmetrical vs. Asymmetrical Multiprocessing (SMP vs. AMP) Modes
The Dual Core ARM
Cyclone® V /
Arria® V HPS can support both Symmetrical Multi-processing
(SMP) and Asymmetrical Multi-processing (AMP) configuration modes.
In SMP mode, a single OS instance controls both cores. The SMP
configuration is supported by a wide variety of operating system manufacturers and is
the most common and straightforward configuration mode for multiprocessing.
Commercially developed operating systems offer features that take full
advantage of the CPU cores resources and use them in an efficient manner resulting in
optimum performance and ease of use. For instance, SMP enabled operating systems offer
the option of setting processor affinity. This means that each task/thread can be
assigned to run on a specific core. This feature allows the software developer to better
control the workload distribution for each
Cortex®-A9 core and making the system more
responsive as an alternative to AMP.
GUIDELINE: Familiarize yourself with the performance and
optimizations available in commercial operating systems to see if an SMP-enabled OS or
RTOS meets your performance and
In the AMP (Asymmetrical Multi-Processing) configuration, two different
operating systems or two instances of a single operating system run on the two cores.
systems have no inherent knowledge of how they share CPU
resources. To ensure
efficient use of MPU subsystem resources in this environment,
must deal with several complex issues when designing your system.
Use AMP only if you are familiar with the techniques to manage and
schedule processes, handle inter-process communication, synchronize between events,
manage secure processes between the two instances of the operating systems.
Note: OS providers do not generally offer support for using their OS in an AMP mode, so
a special support agreement is typically needed in this case.
5.1.3. Assembling your Software Development Platform for Linux
This section presents design guidelines to be used when you have selected Linux as the
OS for your end application.
220.127.116.11. Golden System Reference Design (GSRD) for Linux
The Golden System Reference Design (GSRD) for Linux is provided, which
consists of the following:
GHRD (Golden Hardware Reference Design) - A Quartus Prime
Reference U-Boot based Bootloader
Reference Linux BSP
Sample Linux Applications
Figure 9. GSRD for Linux - Overview
The GSRD for Linux is a well-tested known good design showcasing a
system using both HPS and FPGA resources, intended to be used as a baseline project.
GUIDELINE: To successfully build your software development platform,
it is recommended that you use the GSRD as a baseline project, then modify it to suit
your application needs.
The GSRDs target the
Intel® SoC Development Boards and are provided both in
source and pre-compiled form. They can be obtained from
GUIDELINE: It is recommended that all new projects use the latest
version of GSRD as a baseline.
18.104.22.168. Source Code Management Considerations
The GSRD build process relies on several git trees that are available
Intel® provides Linux* enablement, upstreams to mainline and
collaborates with the Linux*
Intel® provides two kernel
versions, the latest stable kernel (N) and latest LTSI kernel (M) and drops support for
previous Linux* kernel versions (N-1,
M-1). At any point in time the (N, N-1, M, M-1) versions are available from the kernel
repository. Older kernel versions are removed.
GUIDELINE: Manage your own Git repositories and do not assume the
contents of the repositories available on the altera-opensource site remains available.
Managing Git repositories can be achieved in many ways, such as using a Git service
provider. Some benefits of managing your own Git repositories include build
reproducibility, source code management and leveraging the distributed model enabled by
The GSRD uses the Angstrom rootfilesystem, built using Yocto recipes. The recipes pull
in various open source package sources, and build them into the rootfilesystem. Because some of these recipes are generic, and do not refer
to a specific version, the end result may be different from one build to another.
GUIDELINE: If you rebuild the Yocto rootfilesystem and require
repeatability, you must keep a copy of the Yocto downloads folder that was used for the
GUIDELINE: If you rebuild the Angstrom rootfilesystem and require repeatability, you must keep a copy of the Yocto
downloads folder that was used for the build.
22.214.171.124. GSRD for Linux Development Flow
The figure below presents a high-level view of the development flow for
projects based on the GSRD. Refer to the GSRD User Manuals link
given below for more details.
The Linux Device Tree is a data structure that describes the underlying hardware to the
Linux operating system kernel. By passing this data structure the OS kernel, a single OS
binary may be able to support many variations of hardware. This flexibility is
particularly important when the hardware includes an FPGA.
The recommended procedure for managing the Linux Device Tree is:
Start with the SoC FPGA reference Device Trees provided in the
Linux kernel source code that targets the
They cover the HPS portion of the device but do not cover the FPGA portion which
changes on a per-project basis.
are provided with the kernel source code.
Edit the Device Tree as necessary to accommodate any board changes
as compared to the
Edit the Device Tree as necessary to accommodate the Linux drivers targeting FPGA
Note: The GSRD for Linux uses a different flow that the one recommended above relying
on a custom tool called “Linux Device Tree Generator” that is provided as part of SoC
Figure 12. Device Tree Generation Flow for GSRD for Linux
Refer to the DeviceTree Generator User Guide link given below for
more details about the Linux Device Tree Generator.
5.1.4. Assembling a Software Development Platform for a Bare-Metal Application
Intel® hardware libraries (HWLibs) are low level bare
metal software libraries provided with SoC EDS and various components of the HPS. The
HWLibs are also typically used by
Intel®’s OS partners to build board
support packages for operating systems.
The HWLibs have two components:
SoC Abstraction Layer (SoCAL): Symbolic register abstraction later
that enables direct access and control of HPS device registers within the address
Hardware Manager (HWMgr): APIs that provide more complex
functionality and drivers for higher level use case scenarios.
Figure 13. HWLibs Overview
Note that not all hardware is covered by SoCAL and HWMgr, therefore
writing custom code
be necessary depending on
application. Software applications that use
should have run time provisions to manage the resources of the
subsystem, the cache and memory. These provisions are typically what the operating
GUIDELINE: It is recommended using HWLibs only if you are familiar
with developing a run time provision to manage your application.
GUIDELINE: Use the HWLibs Project Generator to create your
customized HWLibs project.
Intel recommends that you
create your custom HWLibs project using the HWLibs Project Generator tool, available on
5.1.5. Assembling your Software Development Platform for a Partner OS or RTOS
Partner OS providers offer board support packages and commercial support
for the SoC FPGA devices. Typically,
support includes example
projects and associated documentation.
Note: Please refer to the
partner documentation and support services for information on how to assemble the
software development platform when targeting a
OS or RTOS.
5.1.6. Choosing Boot Loader Software
Cyclone® V /
Arria® V SoC boot flow includes the following stages:
Cyclone® V /
Arria® V SoC Boot Flow
The BootROM and Preloader stages are needed for all
Cyclone® V SoC /
Arria® V SoC
applications. U-boot and Linux are used by the GSRD, but a custom application may
implement a different flow, such as using the Preloader to load a
Typically, the main responsibilities of the Preloader are:
Perform additional HPS initialization
Bring up SDRAM
Load the next boot stage from Flash to SDRAM and jump to it
Currently, two different Preloader options are available:
SPL - part of U-Boot. Provided with SoC EDS under GPL (Open
MPL - provided with SoC EDS as an example using the HWLibs
(bare-metal libraries). Uses BSD license.
Note: The Preloader requires a special header to be placed at the beginning of the next
stage boot image. Also, the header contains a CRC value used to validate the image.
The header can be attached to an image by using the mkimage utility that is included
with SoC EDS.
The Bootloader has typical responsibilities that are similar with the
Preloader, except it does not need to bring up SDRAM. Because the Bootloader is already
residing in SDRAM, it is not limited by the size of the OCRAM. Therefore, it can provide
a lot of features, such as network stack support.
A typical HPS system had numbers of registers that need to be set for a
given configuration of the
subsystem, the network-on-chip interconnect component, the SDRAM memory, flash boot
source and peripheral interfaces. The settings used for boot or initialization purposes
are encapsulated in the following places:
RBF File(s) - containing register settings for SDRAM also
dedicated I/O and FPGA pin configuration.
U-Boot source code - for rest of the settings
Figure 15. Preloader Build Flow
Note: It is highly
recommended that Preloader is generated with bsp-editor. It is also recommended,
although not required, to build U-Boot from the same source code.
5.1.7. Selecting Software Tools for Development, Debug and Trace
Note: When using a specific Partner OS or RTOS, consult the OS vendor and the OS
documentation for any specific tools that are required. Some OS vendors also provide
a full set of tools that are recommended to be used with that OS.
Note: Familiarize yourself
with the available tools for development, compilation and debug. A list of supported
tools is available at the Ecosystem tab of the
126.96.36.199. Select Software Build Tools
GUIDELINE: Decide which software development tools
development tools include compilers, assemblers, linkers, and archivers.
Development Studio 5* (DS-5*)
Intel® SoC FPGA Edition includes the following software
ARMCC Bare-metal Compiler
Mentor Graphics CodeSourcery Lite GCC-based bare-metal
Linux Linaro Compiler
There are also other development tools offerings from third party
188.8.131.52. Select Software Debug Tools
Intel® SoC FPGA Edition includes a fully featured
Eclipse-based debugging environment. There are also other debugging tools offerings from
third party providers such as Lauterbach T32.
The debug tools require a JTAG connection to the SoC FPGA device. The
connection could be achieved in a couple of ways:
An embedded USB-Blaster II chip could be available on-board such
as on the
Cyclone® V SoC /
Arria® V SoC Development Kit.
External JTAG hardware may be required when using the Lauterbach
184.108.40.206. Select Software Trace Tools
Tracing can be very helpful for profiling performance bottlenecks, debugging crash
scenarios and debugging complex cases. Tracing can be performed in two ways:
Non-real-time: by storing trace data in system memory
example SDRAM) or the embedded trace buffer, then stopping the
system, downloading the trace information and analyzing it.
Real-time: by using an external adapter trace data from the trace port. The
target board needs to support this scenario.
Typically, the debug tools also offer tracing of the embedded software
program execution, but external hardware may be required. For example, the DS-5 provided
with the SoC EDS supports both non-real-time and
tracing. When used for real-time tracing, an additional external trace unit called
“DSTREAM” is required. Lauterbach T32 is a similar
example, in that it needs additional external hardware for real-time tracing.
5.2. Flash Device Driver Design Considerations
The SoC FPGAs support the following types of flash devices: QSPI, NAND,
Note: Please refer to
Supported Flash Devices for
Cyclone® V and
Arria® V SoC
a list of supported flash devices. Use an
Intel® Tested and Supported”
of incompatibility. The next best option is to select a “Known to Work” device. This
means that the device is compatible with BootROM and was proven to work with at least
one Bootloader - but it may not be the Bootloader you need. It may also not have
OS Support or HPS Flash Programmer Support.
5.3. SD Card Low Power Mode Design Considerations
The SD/MMC Controller has a low power mode which is enabled by setting the
cclk_low_power bit of the clkena
register to 1. When this mode takes effect, the clock to the card is disabled when
the card is idle for at least eight card clock cycles.
During this low power mode, the state of the SD I/O signals are as follows:
SD_CLK = 0
SD_CMD = 1
SD_D0..3 = floating
If the end application requires all SD I/O signals to be floating during the low
power mode, the following procedure is recommended:
When the card is not in use, after the last command:
Set the GPIOs associated to the SD_CMD and
SD_CLK pins as inputs by using the
Change the pin muxing for the SD_CLK and
SD_CMD pins to be GPIO signals by using the
When the card is to be used again, before the next command:
Change back the pin muxing for the SD_CLK and
SD_CMD to be SD I/O signals by using the
When the SD/MMC controller is in reset state, the state of the SD I/O signals
is as follows:
SD_CLK = 0
SD_CMD = floating
SD_D0..3 = floating
5.4. HPS ECC Design Considerations
ECC is implemented throughout the entire HPS subsystem on all RAMs,
including the external HPS EMIF, L2 cache data RAMs and all peripheral RAMs. The
controller ECC employs standard Hamming logic to detect and correct single-bit errors
and detect double-bit errors. Parity protection is provided for the
cache memories and L2 tag RAM. ECC can be selectively enabled on the HPS EMIF and
internal HPS RAMs. Diagnostic test modes and error injection capability are available
under software control. ECC is disabled by default upon power-up or cold reset.
The generated boot code configures, initializes and enables ECC according
to user options selected during BSP generation. Custom firmware and bare metal
application code access to the ECC features is facilitated with the
Intel®-provided HWLibs library, which provides a simple
API for programming HPS software features.
Each RAM in the HPS subsystem has its own ECC controller with a unique
set of features and
system integration design
that you should consider.
5.4.2. System-Level ECC Control, Status and Interrupt Management
The System Manager contains a set of ECC-related registers for
system-level control and status for all the ECC controllers in the HPS subsystem.
ECC-related interrupts are also managed through this set of registers.
The L2 cache memory is ECC protected, while the tag RAMs are parity
protected. L2 cache ECC is enabled through a control register in the System Manager.
For details about the L2 cache ECC controller, refer to the following
sections in the "
Cortex®-A9 Microprocessor Unit Subsystem" chapter of the appropriate
Hard Processor System Technical Reference Manual:
“Single Event Upset Protection”
“L2 Cache Controller Address Map for
Cyclone® V” or "L2 Cache Controller Address Map for
GUIDELINE: The L1 and L2 cache must be configured as write-back and
write-allocate for any cacheable memory region with ECC enabled.
For BSPs supported
Intel® SoC FPGA EDS, you can
configure your BSP for ECC support with the bsp-editor utility.
metal firmware, refer to
"L2 Cache Controller
Address Map" in
Cortex®-A9 Microprocessor Unit Subsystem" chapter of the appropriate Hard
Processor System Technical Reference Manual.
GUIDELINE: Cache-coherent accesses through the L3 interconnect using
the ACP must perform 64-bit wide, 64-bit aligned write accesses when ECC is enabled in
the L2 Cache Controller
Enabling ECC does not affect the performance of the L2 cache, but
accesses using the ACP must be 64-bit wide, 64-bit aligned in memory. This includes FPGA
accessing the ACP over the FPGA-to-HPS Bridge.
For a list of
possible combinations of bridge width and FPGA master width, alignment and burst size
Access to ACP" in the "HPS-FPGA Bridges" chapter of the appropriate Hard Processor System Technical Reference
All peripheral RAMs in the HPS subsystem are ECC protected. The NAND
flash controller ECC hardware is not used when a read-modify-write operation is
performed from the flash device’s page buffer. Software must update the ECC during such
read-modify-write operations. For a read-modify-write operation to work with hardware
ECC, the entire page must be read into system memory, modified, then written back to
flash without relying on the flash device’s read-modify-write feature.
The NAND flash controller cannot do ECC validation during a copy-back
command. The flash controller copies the ECC data but does not validate it during the
5.5. HPS SDRAM Considerations
5.5.1. Using the Preloader To Debug the HPS SDRAM
To debug the HPS EMIF, you can change the settings in the preloader to
enable runtime calibration report, debug level information and check the status of HPS
runtime calibration report, use your preferred editor to open the
file and configure the RUNTIME_CAL_REPORT value to
220.127.116.11. Change DLEVEL To Get More Debug Information
18.104.22.168. Enable Example Driver for HPS SDRAM
Enable with Hardware Diagnostic Option in bsp-editor. Note:
Example driver is only available in
Quartus® Prime version 14.0 and
PRBS31 Data pattern
Write to random address => Read from random address
Can select different coverage by changing parameter in
22.214.171.124. Change Data Pattern in Example Driver
Path for sdram_test.c:
Change the test_rand_address function
126.96.36.199. Example Code to Write and Read from All Addresses
188.8.131.52. Read/Write to HPS Register in Preloader
Use the following function:
writel to write to HPS register
readl to read from HPS register
184.108.40.206. Check HPS PLL Lock Status in Preloader
Read HPS PLL Status Register in
clock_manager.c and print out in
Define global variable in
clock_manager.c and “extern variable” in
Unable to printout value in
clock_manager.c as the UART has not been initialized
5.5.2. Access HPS SDRAM via the FPGA-to-SDRAM Interface
The HPS bridges can be enabled from the Preloader (SPL/MPL) or U-Boot and
in some cases from Linux.
Note: Preloaders (SPL) and
U-Boot generated from SoC EDS 13.1 and later contain extra functionality and built in
functions to safely enable the HPS bridges.
To enable the HPS FPGA-to-SDRAM bridge from the Preloader or U-Boot,
follow the appropriate steps.
Enabling HPS-to-FPGA Bridges from the Preloader
The Preloader checks the status of the FPGA and automatically enables
bridges configured in
Platform Designer (Standard) and the BSP if the FPGA is configured. The
Preloader supports programming the FPGA before running automatic bridge enable tests and
The bridge_enable_handoff command can
be run from the U-boot command prompt to enable bridges. This command puts the HPS and
SDRAM into a safe state before enabling all bridges after appropriate checks.
Technical support for operating system board support packages (BSPs) that
are ported to the
Intel® SoC development kit is provided by
the operating system provider.
Support for the
Intel® SoC FPGA Embedded Development Suite (SoC EDS) and the design tools for
FPGA development are provided by
Intel®. The SoC EDS includes the
Development Studio 5* for Intel® SoC FPGA Edition Toolkit.
Support of the
Intel® SoC development kit is
Technical Support for other boards is provided by the respective board provider or
Commercial operating system and tools
Operating System and Tools Vendor
HardwareLibs (Bare Metal)
Intel® SoC FPGA EDS
DS-5* for Intel® SoC FPGA Edition
Open Source and Linux*
For additional information, please refer to these links given below.
B.1. Cyclone V and Arria V SoC Device Guidelines Revision History
The following sections were updated:
Embedded Software Design
Guidelines for SoC FPGAs section:
Added Source Code
Added SD Card Low Power Mode Design
Design Guidelines for HPS portion of SoC
Avoid ACP Dependency
Added HPS Address Mirroring under the
Design Guidelines for HPS portion of SoC FPGAs
section to describe HPS SDRAM mirror rank support in SoC.
Updated the Early Power Estimation section to include
information for CVSoC L.
Update product names
"Background: Comparison between SoC FPGA
and SoC FPGA HPS Subsystem" chapter:
Remove overview and block
diagram of L3 interconnect
Remove SDRAM controller block
Clarify description of
Remove detailed descriptions of
HPS-FPGA system topologies
Use the lightweight
HPS-to-FPGA bridge to connect IP that needs to be
controlled by the HPS.
Do not use the lightweight
HPS-to-FPGA bridge for FPGA memory. Instead use
the HPS-to-FPGA bridge for memory.
Use the HPS-to-FPGA bridge to
connect memory hosted by the FPGA to the
If memory connected to the
HPS-to-FPGA bridge is used for HPS boot, ensure
that its slave address is set to 0x0 in Platform Designer (Standard).
Use the FPGA-to-HPS bridge for
cacheable accesses to the HPS from masters in the
Use the FPGA-to-HPS bridge to
access cache-coherent memory, peripherals, or
on-chip RAM in the HPS from masters in the
Use the FPGA-to-SDRAM ports
for non-cacheable access to the HPS SDRAM from
masters in the FPGA.
"Design Guidelines for HPS portion of
SoC FPGAs" chapter:
Cyclone® V HPS-FPGA Bridge
Reference Design Example instead of the
Cyclone® V Datamover Design
GPIO not recommended for
high-speed serial interfaces
Use the Golden System
Reference Design (GSRD) as a starting point for a
loosely coupled system.
Cyclone® V HPS-to-FPGA
Bridge Design Example reference design to
determine your optimum burst length and data-width
for accesses between FPGA logic and HPS.
Intel® recommends that you use
the Golden System Reference Design (GSRD) as a
starting point for a loosely coupled system.
Intel recommends that you use the
Cyclone® V HPS-FPGA
Bridge Reference Design Example to optimize your
hardware design and software solutions to achieve
high performance real time application with HPS
"Board Design Guidelines for SoC FPGAs"
RGMII supported by HPS dedicated
If your design uses QSPI flash
with 4-byte addressing, design the board to ensure
that the QSPI flash is reset or power-cycled
whenever the HPS is reset.
If your SPI peripheral
requires the SPI master slave select to stay low
during the entire transaction period, consider
using GPIO as slave select, or configure the SPI
master to assert slave select during the
Ensure that the SD/MMC card is
reset whenever the HPS is reset.
For bare-metal applications,
avoid using a QSPI flash device larger than 16
With a QSPI device larger than
16 MB, use QSPI extended 4-byte addressing
commands if supported by the device
"Embedded Software Design Guidelines for
SoC FPGAs" chapter:
Reference DTB for NAND-based
boot no longer supplied
Clarify NAND flash interface
type required for booting support