R-Tile Avalon® Streaming Intel® FPGA IP for PCI Express* User Guide

ID 683501
Date 12/06/2024
Public

A newer version of this document is available. Customers should click here to go to the newest version.

Document Table of Contents

2.2.2.2.1. REFCLK and PERST Guidelines When Using Independent PERST Pins

In Configuration Mode 1 (2x8 Endpoint only), the independent PERST and REFCLK are available with:
  • The IP parameter Enable Independent Perst pins set to enabled.
  • The clock source for refclk2 must be always running.
  • refclk2 does not require a specific Quartus Setting File assignment for its pin location. You must not make a specific location assignment for this pin. The Quartus® Prime software tool selects the corresponding pin location based on the location assignments made for the rest of the R-Tile pins.
  • The pin_perst_n pin must qualify the stability of refclk2.
  • The pin_perst_n pin has the highest priority and toggling it affects both Port 0 and Port 1.
  • You must have a weak pull-down on the pin_perst0_n/pin_perst1_n pins if the corresponding port is not supplied with a reference clock (refclk0/1) during the FPGA configuration. Failing to meet this requirement may cause both ports to fail to link up when pin_perst_n is toggled once configuration is complete and the reference clock (refclk0/1) is not available. Toggling pin_perst_n or the corresponding pin_perst0_n/pin_perst1_n after the FPGA configuration completion will not recover the links and the FPGA will need to be reconfigured.
  • For Port 0 (P0):
    • The clock source comes from refclk0.
    • The reset source can come from pin_perst0_n at the package level or p0_warm_perst_n_i.
  • For Port 1 (P1):
    • The clock source comes from refclk1.
    • The reset source can come from pin_perst1_n at the package level or p1_warm_perst_n_i.