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Serial RapidIO Simple Communication Example for the PXIe-6592R High-Speed Serial Instrument

Overview

The Serial RapidIO Simple Communication sample project demonstrates how to stream data between one or multiple FPGA targets and/or hosts using the Serial RapidIO high-speed serial protocol. Use DMA FIFOs to stream data between the Host and FPGA. Transmit/receive the stream data via Xilinx Serial RapidIO at 3.125 Gb/s on the NI PXIe-6592R. The CLIP supports two independent x1 Serial RapidIO links on Port 0 and Port 1. If modifications are to be made to the SRIO IP core, follow the steps in the attached guide "SRIO Vivado Guide.docx"

 

Description

This sample project assumes basic familiarity with the Serial RapidIO protocol. This document provides a basic overview of portions of the protocol. For more information, please refer to the Xilinx LogiCORE IP Serial RapidIO Gen2 Endpoint v3.1 Product Guide for Vivado Design Suite (PG007).

The included Serial RapidIO core is configured to run two independent ports (Port 0 and Port 1) at 3.125 Gbps. It uses the Initiator/Target style of I/O port using the HELLO packet format.

This project contains four top-level host VIs:

  • Example - SRIO Initiator (Host).vi
  • Example - SRIO Target (Host).vi
  • Example - Prepopulate Memory (Host).vi
  • Example - Acquire Eye Scan (Host).vi

and one top-level FPGA VI:

  • Example - SRIO Controller (FPGA).vi

Project Diagram

NI-PXIe-6592R-SRIO-Simple-Communication.gif

This diagram illustrates the data flow through this example and shows how hardware, software, and data interact. The illustration shows Port 0 as the Initiator and Port 1 as the Target. The Initiator sends transaction packets to the Target, which processes the transaction packets and may send response packets back to the Initiator. This example also supports connecting between two different NI 6592R targets.

The following steps describe data flow in the application:

  1. Example - SRIO Initiator (Host).vi configures the Serial RapidIO packet type and fields and sends data to be transferred from the host to the FPGA through the appropriate Initiator Request DMA FIFO.
  2. The FPGA processes that data and generates the appropriate Serial RapidIO packet(s).
  3. The packet(s) are transmitted out an AXI4-Stream TX endpoint to the Serial RapidIO Protocol IP.
  4. The Serial RapidIO CLIP interfaces with the MGTs (Multi-Gigabit Transceivers) on each port, which serially transmit data across the cable.
  5. Data are received by the designated NI 6592R receiver target through a Serial RapidIO RX endpoint on the chosen port.
  6. The received data are interpreted as Serial RapidIO packets and processed.
  7. The target writes received data to the host via the appropriate Target Request DMA FIFO, where Example - SRIO Target (Host).vi displays the data.
  8. If required, a response is packetized on the FPGA and sent back across the cable, processed, and response data written to the appropriate Response DMA FIFO, where it is displayed by Example - SRIO Initiator (Host).vi.

Serial RapidIO Packet Basics

This sample project provides support for the following Serial RapidIO transaction types:

Transaction Type Description Expected Response
NREAD Requests an amount of data from the target from the specified memory address. Response with data
NWRITE Sends an amount of data to the target starting at the specified memory address. No Response
NWRITE_R Sends an amount of data to the target starting at the specified memory address. Expects an acknowledgement response without data. Response with no data
SWRITE An optimized, streaming write that sends an amount of data to the target starting at the specified memory address. Uses fewer header fields than NWRITE. No Response
DOORBELL Sends a very short message using the 16-bit info field. Doorbell packets contain no address or data. Response with no data
MESSAGE

Sends an amount of data to the target starting at the specified memory address. Allows sending larger data more efficiently than an NWRITE, NWRITE_R, or SWRITE command by breaking the data into message segments instead of new packets.

There are multiple restrictions on MESSAGE transaction data sizes and message length. Message length (the number of segments) cannot be more than 16. All segments must be of the same size (1, 2, 4, 8, 16, or 32 DWORDs), except for the last one, which may be smaller than the other segments.

Messages target a mailbox and letter for delivery. This sample project uses Mailbox 0 for Port 1 and Mailbox 1 for Port 0. All received data is also placed in the appropriate Target Request FIFO.

The Sample Project prevents you from sending invalid MESSAGE transactions.

Message Response (No data)
Atomic Increment Returns the data (1, 2, or 4 bytes) from the specified memory address. After a response is sent, the value at that address is incremented. Response with data
Atomic Decrement Returns the data (1, 2, or 4 bytes) from the specified memory address. After a response is sent, the value at that address is decremented. Response with data
Atomic Set Returns the data (1, 2, or 4 bytes) from the specified memory address. After a response is sent, the value at that address is set to all 1s. Response with data
Atomic Clear Returns the data (1, 2, or 4 bytes) from the specified memory address. After a response is sent, the value at that address is set to all 0s. Response with data
Atomic Swap Returns the data (1, 2, or 4 bytes) from the specified memory address. After a response is sent, the value at that address is replaced with the write data. Response with data
Atomic Compare-and-Swap Returns the data (8 bytes) from the specified memory address. After a response is sent, the value at that address is compared with the first 8 bytes of the write data. If the values are equal, the second 8 bytes of data are written to the memory location. If the values are not equal, no data are written. Response with data
Atomic Test-and-Swap Returns the data (1, 2, or 4 bytes) from the specified memory address. After a response is sent, if the value at the address is 0, then the second DWORD of data is written to the memory location. Response with data

Note that with Atomic operations, because the data is received before the data on the target is updated, repeated Atomic operations may return data that appears to be "off by one". This is intentional and expected behavior of Atomic operations.

Sample Project Behavior

Splitting Data into Multiple Packets

If you attempt to send or receive more data than supported in a single packet when using NWRITE, NWRITE_R, SWRITE, or NREAD, the FPGA splits your request into multiple consecutive packets. For example, an NWRITE packet has a maximum of 32 DWORDs of data. If you attempt to send 128 DWORDs, the FPGA will create and send 4 NWRITE packets, each with 32 DWORDs of data.

Serial RapidIO Device ID

In the Serial RapidIO protocol, each endpoint has a Device ID. When a transaction is received, the endpoint compares the transaction's target ID against its own device ID and will only process the transaction if they match. The Device ID is editable.

In Example - SRIO Target (Host).vi, the current Device ID is read at start and displayed on the Front Panel. To change the target's Device ID, change the value in the Device ID control and press the Write Device ID button. Subsequent transactions to this target must use the new Device ID.

The Target ID on the Example - SRIO Initiator (Host).vi must match the Device ID on the Target in order for transactions to be successfully received. The initiator sends its own Device ID as part of the transaction, and responses from the Target include the Initiator's Device ID to ensure that the response reaches the correct endpoint.

Supported Ports

Although the NI 6592R has 4 ports, this sample project uses a Serial RapidIO core which only instantiates ports 0 and 1. You may connect port 0 and 1 on one NI 6592R or connect ports on two different devices.

 

Hardware and Software Requirements

  • NI PXIe-6592R High-Speed Serial Instrument
    • SFP+ Cable if utilizing device in loop-back or other cabling as required
  •  LabVIEW 2015 or later
  • LabVIEW FPGA Module

 

Steps to Implement or Execute Code

Running this Sample Project

  1. Connect the high-speed serial ports on the front panel of your NI PXIe-6592R. This example supports connecting Port 0 to 1 on one NI 6592R or connecting between two different NI 6592R devices.
  2. Open Example - SRIO Target (Host).vi under the SRIO Simple Controller (NI 6592R) (Host).lvlib library.
    1. Select an NI 6592R RIO alias from the RX FPGA Resource drop-down and select a receiver port consistent with your cabling set-up before running the VI.
    2. Run Example - SRIO Target (Host).vi. The receiver stream is now waiting for data from the transmitter. Note the Device ID.
  3. Open Example - SRIO Initiator (Host).vi under the SRIO Simple Communication (NI 6592R) (Host).lvlib library.
    1. Select an NI 6592R RIO alias from the TX FPGA Resource drop-down and select a transmitter port consistent with your cabling set-up before running the VI.
    2. Configure the Target ID to match that of the Device ID on the Example - SRIO Target (Host).vi.
    3. Run Example - SRIO Initiator (Host).vi. Change Packet Type to select the type of packet you wish to send. The configurable fields for the selected Packet Type will be automatically enabled.
    4. Configure the packet settings, then click Send TX Packet to transmit the data to the FPGA. The FPGA then processes the data and sends it to the target port.
  4. The Received Waveform, Received Data, Latest Received Packet Type, and Latest Received Info on Example - SRIO Target (Host).vi display received data.
  5. Received Response Waveform and Received Response Data on Example - SRIO Initiator (Host).vi display information from response packets.
  6. Click Stop to stop the Example - SRIO Initiator (Host).vi.
  7. Click Stop to stop the Example - SRIO Target (Host).vi.

Pre-populating Memory Before Running the Sample Project

Use Example - Prepopulate Memory (Host).vi to write data directly to the FPGA's memory space. This method populates the device memory with known values.

Generating and Integrating Serial RapidIO IP into Your LabVIEW Project

For information about how to integrate Xilinx IP into a LabVIEW project, refer to Knowledge Base article 6R6EOLM3.

Troubleshooting Signal Integrity Issues

An Eye Scan allows you to determine the quality of your link statistically. To run an Eye Scan on a receiver, follow these steps:

  1. Open Example - Acquire Eye Scan (Host).vi under the SRIO Simple Communication (NI 6592R) (Host).lvlib library.
  2. Select an NI 6592R RIO alias from the FPGA Resource drop-down and select a port to perform an Eye Scan on before running the VI.
  3. Run the VI.
  4. The graph will update to show you an Eye Diagram that represents the quality of the high-speed data link.

For more information regarding Eye Scan, consult the section on Eye Scan Theory in the Xilinx 7 Series FPGAs GTX/GTH Transceivers User Guide (UG476).

If you are trying to stream between two different devices and receive an error because the port is not ready but your cables are connected, run the VI on the other device and try again. There must be an active Serial RapidIO core on both sides of the connection for a high-speed serial link to be established.

 

Comments
Cece-Zheng
NI Employee

Hi Johnnyg17. Recently I am working on a POC and I found your article is really help for me. but  I still run into several problems. Could you please help me ? 1.I followed the steps in the attached guide "SRIO Vivado Guide.docx" and I completed all the steps.but the .xci file won't appear in the CLIP file folder automaticly,I need to copy it and add to the folder.Is that right?  2.If I want to run the program, I need to compile the FPGA.vi, right? How to chose the top clock? Should I choose the PXIe-CLK100 or on board clock? 3.When I compile the FPGA.vi,always failed,I don't know where the problem is. That's all the problem I met now,hope that you could give me some information or solution,Thank you very much! 

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