AN 796: Cyclone® V and Arria® V SoC Device Design Guidelines

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ID 683360
Date 3/30/2022
Public
Document Table of Contents
Document Table of Contents x
1. Overview of the Design Guidelines for Cyclone® V SoC FPGAs and Arria® V SoC FPGAs 2. Background: Comparison between Cyclone® V SoC FPGA and Arria® V SoC FPGA HPS Subsystems 3. Design Guidelines for HPS portion of SoC FPGAs 4. Board Design Guidelines for SoC FPGAs 5. Embedded Software Design Guidelines for SoC FPGAs A. Support and Documentation B. Additional Information
1. Overview of the Design Guidelines for Cyclone® V SoC FPGAs and Arria® V SoC FPGAs x
1.1. The SoC FPGA Designer’s Checklist 1.2. Overview of HPS Design Guidelines for SoC FPGA design 1.3. Overview of Board Design Guidelines for SoC FPGA Design 1.4. Overview of Embedded Software Design Guidelines for SoC FPGA Design
2. Background: Comparison between Cyclone® V SoC FPGA and Arria® V SoC FPGA HPS Subsystems x
2.1. Guidelines for Interconnecting the HPS and FPGA
2.1. Guidelines for Interconnecting the HPS and FPGA x
2.1.1. HPS-FPGA Bridges 2.1.2. FPGA-to-HPS SDRAM Access 2.1.3. Connecting Soft Logic to HPS Component
2.1.1. HPS-FPGA Bridges x
2.1.1.1. Lightweight HPS-to-FPGA Bridge 2.1.1.2. HPS-to-FPGA Bridge 2.1.1.3. FPGA-to-HPS Bridge
3. Design Guidelines for HPS portion of SoC FPGAs x
3.1. Start your SoC-FPGA design here 3.2. Design Considerations for Connecting Device I/O to HPS Peripherals and Memory 3.3. HPS Clocking and Reset Design Considerations 3.4. HPS EMIF Design Considerations 3.5. DMA Considerations 3.6. Managing Coherency for FPGA Accelerators 3.7. IP Debug Tools
3.1. Start your SoC-FPGA design here x
3.1.1. Recommended Starting Point for HPS-to-FPGA Interface Design 3.1.2. Determining your SoC FPGA Topology
3.2. Design Considerations for Connecting Device I/O to HPS Peripherals and Memory x
3.2.1. HPS Pin Assignment Design Considerations 3.2.2. HPS I/O Settings: Constraints and Drive Strengths
3.3. HPS Clocking and Reset Design Considerations x
3.3.1. HPS Clock Planning 3.3.2. Early Pin Planning and I/O Assignment Analysis 3.3.3. Pin Features and Connections for HPS JTAG, Clocks, Reset and PoR 3.3.4. Internal Clocks
3.4. HPS EMIF Design Considerations x
3.4.1. Considerations for Connecting HPS to SDRAM 3.4.2. HPS SDRAM I/O Locations 3.4.3. Integrating the HPS EMIF with the SoC FPGA Device 3.4.4. HPS Memory Debug 3.4.5. HPS Address Mirroring
3.5. DMA Considerations x
3.5.1. Choosing a DMA Controller 3.5.2. Optimizing DMA Master Bandwidth through HPS Interconnect 3.5.3. Timing Closure for FPGA Accelerators
3.6. Managing Coherency for FPGA Accelerators x
3.6.1. Cache Coherency 3.6.2. Coherency between FPGA Logic and HPS: Accelerator Coherency Port (ACP) 3.6.3. Data Size Impacts ACP Performance 3.6.4. Avoiding ACP Dependency Lockup 3.6.5. FPGA Access to ACP via AXI* or Avalon-MM 3.6.6. Data Alignment for ACP and L2 Cache ECC accesses
4. Board Design Guidelines for SoC FPGAs x
4.1. Board Bring Up Considerations 4.2. Boot and Configuration Design Considerations 4.3. HPS Power Design Considerations 4.4. Boundary Scan for HPS 4.5. Design Guidelines for HPS Interfaces
4.1. Board Bring Up Considerations x
4.1.1. Reserved BSEL Setting
4.2. Boot and Configuration Design Considerations x
4.2.1. Boot Design Considerations 4.2.2. Configuration 4.2.3. Reference Materials
4.2.1. Boot Design Considerations x
4.2.1.1. Boot Source 4.2.1.2. Select Desired Flash Device 4.2.1.3. BSEL Options 4.2.1.4. Boot Clock 4.2.1.5. CSEL Options 4.2.1.6. Selecting NAND Flash Devices 4.2.1.7. Determine Flash Programming Method 4.2.1.8. For QSPI and SD/MMC/eMMC Provide Flash Memory Reset 4.2.1.9. Selecting QSPI Flash Devices
4.2.2. Configuration x
4.2.2.1. Traditional Configuration 4.2.2.2. HPS Initiated Configuration
4.3. HPS Power Design Considerations x
4.3.1. Early System and Board Planning 4.3.2. Design Considerations for HPS and FPGA Power Supplies for SoC FPGA devices 4.3.3. Pin Connection Considerations for Board Designs 4.3.4. Power Analysis and Optimization
4.3.1. Early System and Board Planning x
4.3.1.1. Early Power Estimation
4.3.2. Design Considerations for HPS and FPGA Power Supplies for SoC FPGA devices x
4.3.2.1. Consider the Need to Power Down the FPGA Portion While Keeping the HPS Running 4.3.2.2. Consider Desired HPS Boot Clock Frequency
4.3.3. Pin Connection Considerations for Board Designs x
4.3.3.1. Device Power-Up
4.5. Design Guidelines for HPS Interfaces x
4.5.1. HPS EMAC PHY Interfaces 4.5.2. USB Interface Design Guidelines 4.5.3. QSPI Flash Interface Design Guidelines 4.5.4. SD/MMC and eMMC Card Interface Design Guidelines 4.5.5. NAND Flash Interface Design Guidelines 4.5.6. UART Interface Design Guidelines 4.5.7. I2C Interface Design Guidelines 4.5.8. SPI Interface Design Guidelines
4.5.1. HPS EMAC PHY Interfaces x
4.5.1.1. PHY Interfaces Connected Through HPS Dedicated I/O 4.5.1.2. PHY Interfaces Connected Through FPGA I/O 4.5.1.3. Common PHY Interface Design Considerations
4.5.1.1. PHY Interfaces Connected Through HPS Dedicated I/O x
4.5.1.1.1. RGMII I/O Pin Timing Transmit path setup/hold GUIDELINE: Ensure your design includes the necessary Quartus settings to configure the HPS EMAC outputs for the required delays. Receive path setup/hold GUIDELINE: Hardware developers should specify the required FPGA skew so that software developers can add the skew to the device driver code.
4.5.1.2. PHY Interfaces Connected Through FPGA I/O x
4.5.1.2.1. GMII/MII 4.5.1.2.2. Adapting to RGMII 4.5.1.2.3. Adapting to RMII 4.5.1.2.4. Adapting to SGMII 4.5.1.2.5. MDIO
4.5.1.3. Common PHY Interface Design Considerations x
4.5.1.3.1. Signal Integrity
5. Embedded Software Design Guidelines for SoC FPGAs x
5.1. Embedded Software for HPS: Design Guidelines 5.2. Flash Device Driver Design Considerations 5.3. SD Card Low Power Mode Design Considerations 5.4. HPS ECC Design Considerations 5.5. HPS SDRAM Considerations
5.1. Embedded Software for HPS: Design Guidelines x
5.1.1. Assembling the Components of Your Software Development Platform 5.1.2. Selecting an Operating System for Your Application 5.1.3. Assembling your Software Development Platform for Linux 5.1.4. Assembling a Software Development Platform for a Bare-Metal Application 5.1.5. Assembling your Software Development Platform for a Partner OS or RTOS 5.1.6. Choosing Boot Loader Software 5.1.7. Selecting Software Tools for Development, Debug and Trace
5.1.1. Assembling the Components of Your Software Development Platform x
5.1.1.1. Golden Hardware Reference Design
5.1.2. Selecting an Operating System for Your Application x
5.1.2.1. Linux or RTOS 5.1.2.2. Bare Metal 5.1.2.3. Using Symmetrical vs. Asymmetrical Multiprocessing (SMP vs. AMP) Modes
5.1.3. Assembling your Software Development Platform for Linux x
5.1.3.1. Golden System Reference Design (GSRD) for Linux 5.1.3.2. Source Code Management Considerations 5.1.3.3. GSRD for Linux Development Flow 5.1.3.4. GSRD for Linux Build Flow 5.1.3.5. Linux Device Tree Design Considerations
5.1.7. Selecting Software Tools for Development, Debug and Trace x
5.1.7.1. Select Software Build Tools 5.1.7.2. Select Software Debug Tools 5.1.7.3. Select Software Trace Tools
5.4. HPS ECC Design Considerations x
5.4.1. General ECC Design Considerations 5.4.2. System-Level ECC Control, Status and Interrupt Management 5.4.3. ECC for L2 Cache Data Memory 5.4.4. ECC for Flash Memory
5.5. HPS SDRAM Considerations x
5.5.1. Using the Preloader To Debug the HPS SDRAM 5.5.2. Access HPS SDRAM via the FPGA-to-SDRAM Interface
5.5.1. Using the Preloader To Debug the HPS SDRAM x
5.5.1.1. Enable Runtime Calibration Report 5.5.1.2. Change DLEVEL To Get More Debug Information 5.5.1.3. Enable Example Driver for HPS SDRAM 5.5.1.4. Change Data Pattern in Example Driver 5.5.1.5. Example Code to Write and Read from All Addresses 5.5.1.6. Read/Write to HPS Register in Preloader 5.5.1.7. Check HPS PLL Lock Status in Preloader
A. Support and Documentation x
A.1. Support A.2. Software Documentation
B. Additional Information x
B.1. Cyclone® V and Arria® V SoC Device Guidelines Revision History
1. Overview of the Design Guidelines for Cyclone® V SoC FPGAs and Arria® V SoC FPGAs
2. Background: Comparison between Cyclone® V SoC FPGA and Arria® V SoC FPGA HPS Subsystems
3. Design Guidelines for HPS portion of SoC FPGAs
4. Board Design Guidelines for SoC FPGAs
5. Embedded Software Design Guidelines for SoC FPGAs
A. Support and Documentation
B. Additional Information

4.5.1.1.1. RGMII

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 Cyclone® V/ Arria® V HPS Dedicated I/O does not feature programmable delay.

For TX_CLK from the Cyclone® V/ 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 datapaths.

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.

On the Cyclone® V/ 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 Microchip* (Micrel*) KSZ9021RN PHY. Refer to the hps_common_board_info.xml 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 Cyclone® V/ 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.

The hps_common_board_info.xml file is used to compile the Linux device tree for the Cyclone® V or Arria® V SoC GSRD.

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