R-tile Avalon® Streaming Intel® FPGA IP for PCI Express* Design Example User Guide

ID 683544
Date 3/28/2022

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Document Table of Contents PIO Design Example

The figure below shows the PIO design example simulation design hierarchy. The tests for the PIO design example are defined with the apps_type_hwtcl parameter set to 3. The tests run under this parameter value are defined in ebfm_cfg_rp_ep_rootport, find_mem_bar and downstream_loop.

Figure 17. PIO Design Example Simulation Design Hierarchy
The testbench starts with link training and then accesses the configuration space of the IP for enumeration. A task called downstream_loop (defined in the Root Port PCIe BFM altpcietb_bfm_rp_gen5_x16.sv) then performs the PCIe link test. This test consists of the following steps:
  1. Issue a memory write command to write a single dword of data into the on-chip memory behind the Endpoint.
  2. Issue a memory read command to read back data from the on-chip memory.
  3. Compare the read data with the write data. If they match, the test counts this as a Pass.
  4. Repeat Steps 1, 2 and 3 for 10 iterations.

The first memory write takes place around 219 us. It is followed by a memory read at the Avalon® -ST RX interface of the R-tile Hard IP for PCIe. The Completion TLP appears shortly after the memory read request at the Avalon® -ST TX interface.

Note: In the 2x8 design example, memory read and memory write transactions are simulated on Port 0 only.