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AR# 63218

2013.x,2014.x Vivado Constraints - Dual Data Rate (DDR) incorrect XDC Language Template

Description

In Vivado versions prior to 2015.1, The below XDC Language Template is incorrect:

XDC -> Timing constraints -> Input Delay Constraints -> Source synchronous -> Edge Aligned (Clock directly to FF) -> Dual Data Rate (DDR)

set_input_delay -clock $input_clock -max [expr $input_clock_period/2 + $skew_afe] [get_ports $input_ports];
set_input_delay -clock $input_clock -min [expr $input_clock_period/2 - $skew_bre] [get_ports $input_ports];
set_input_delay -clock $input_clock -max [expr $input_clock_period/2 + $skew_are] [get_ports $input_ports] -clock_fall -add_delay;
set_input_delay -clock $input_clock -min [expr $input_clock_period/2 - $skew_bfe] [get_ports $input_ports] -clock_fall -add_delay;

Solution

The correct template should be as follows:

set_input_delay -clock $input_clock -max [expr $input_clock_period/2 + $skew_afe] [get_ports $input_ports];
set_input_delay -clock $input_clock -min [expr $input_clock_period/2 - $skew_bfe] [get_ports $input_ports];
set_input_delay -clock $input_clock -max [expr $input_clock_period/2 + $skew_are] [get_ports $input_ports] -clock_fall -add_delay;
set_input_delay -clock $input_clock -min [expr $input_clock_period/2 - $skew_bre] [get_ports $input_ports] -clock_fall -add_delay;

This issue has been fixed in the 2015.1 release.
AR# 63218
Date Created 12/22/2014
Last Updated 01/12/2015
Status Active
Type General Article
Tools
  • Vivado Design Suite - 2013.2
  • Vivado Design Suite - 2013.3
  • Vivado Design Suite - 2013.4
  • More
  • Vivado Design Suite - 2014.1
  • Vivado Design Suite - 2014.2
  • Vivado Design Suite - 2014.3
  • Vivado Design Suite - 2014.4
  • Less