Stratix V Avalon-MM Interface for PCIe Solutions: User Guide

ID 683411
Date 5/21/2017
Public
Document Table of Contents

10.4. SDC Timing Constraints

Note: You may need to change the name of the Reconfiguration Controller clock, reconfig_xcvr_clk, to match the clock name used in your design. The following error message indicates that TimeQuest could not match the constraint to any clock in your design:
Ignored filter at altpcied_sv.sdc(25): *reconfig_xcvr_clk* could not be matched with a port or pin or register or keeper or net

SDC Timing Constraints Required for the Stratix V Hard IP for PCIe and Design Example

 
# Constraints required for the Hard IP for PCI Express
# derive_pll_clock is used to calculate all clock derived from 
# PCIe refclk. It must be applied  once across all of the SDC
# files used in a project 
create_clock -period "100 MHz" -name {refclk_clk} {*refclk_clk*}
derive_pll_clocks -create_base_clocks  
derive_clock_uncertainty 
#########################################################################
# Reconfig Controller IP core constraints
# Set reconfig_xcvr clock: 
# this line will likely need to be modified to match the actual
# clock pin name used for this clock, and also changed to have
# the correct period set for the clock actually used  
create_clock -period "125 MHz" -name {reconfig_xcvr_clk}
				  {*reconfig_xcvr_clk*} 				 
######################################################################	 
# Hard IP testin pins SDC constraints 
set_false_path -from [get_pins -compatibility_mode *hip_ctrl*]
######################################################################	
# These additional constraints are for Gen3 only
set_false_path -from [get_clocks {reconfig_xcvr_clk}]  -to [get_clocks 
{*|altpcie_hip_256_pipen1b|stratixv_hssi_gen3_pcie_hip|coreclkout}]
set_false_path -from [get_clocks {*|altpcie_hip_256_pipen1b|
stratixv_hssi_gen3_pcie_hip|coreclkout}]  -to  
[get_clocks {reconfig_xcvr_clk}]

Additional .sdc timing are in the /<project_dir>/synthesis/submodules directory.

SDC Constraints for the Hard IP for PCIe

In the example above, you should only apply the first three constraints, in one location across all of the SDC files in your project. Differences between Fitter timing analysis and TimeQuest timing analysis arise if these constraints are applied multiple times.

SDC Constraints for the Qsys Example Design

The .sdc file includes constraints for the Transceiver Reconfiguration Controller IP Core which is included in the Qsys example designs. You may need to change the frequency and actual clock pin name to match your design. The .sdc file also specifies some false timing paths for Transceiver Reconfiguration Controller and Transceiver PHY Reset Controller IP Cores. Be sure to include these constraints in your .sdc file.