Intel® Agilex™ Configuration User Guide

ID 683673
Date 5/30/2022
Public

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3.1.7.4.1. PFL II IP Recommended Design Constraints to FPGA Avalon-ST Pins

Create a pfl_clk clock and a generated AVST_CLK clock

Example below creates a pfl_clk clock running at 50 MHz, supplied by the clk_50m_sysmax input clock.

set pfl_clk_period 20.000
create_clock -name {clk_50m_sysmax} -period $pfl_clk_period [get_ports {clk_50m_sysmax}]
create_generated_clock -name AVST_CLK -source [get_ports {clk_50m_sysmax}] [get_ports {avst_clk}]

Set output delay for PFL II IP output pins

Example below sets the output delay for the AvST_DATA and AvST_VALID pins.

set avst_data_tracemax 0.250
set avst_data_tracemin 0.000
set avst_clk_tracemax 0.250
set avst_clk_tracemin 0.000
set fpga_Tsu 2.100
set fpga_Th 0.100
set fpga_out_max_dly [expr $avst_data_tracemax + $fpga_Tsu - $avst_clk_tracemin]
set fpga_out_min_dly [expr $avst_data_tracemin - $fpga_Th - $avst_clk_tracemax]

set_output_delay -add_delay -max -clock [get_clocks {AVST_CLK}] $fpga_out_max_dly [get_ports {avst_d[*] avst_valid}]
set_output_delay -add_delay -min -clock [get_clocks {AVST_CLK}] $fpga_out_min_dly [get_ports {avst_d[*] avst_valid}]

Setting a false path

You can set the AVST_READY input pin to a false path since this pin is not synchronous to the AVST_CLK clock. The host must synchronize the AVST_READY signal to the AVST_CLK signal using a 2-stage register synchronizer.

set_false_path -from [get_ports {avst_ready}] -to * 

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