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AR# 38554

12.3 Timing/Constraint - How to control skew of the paths through combinational logic

Description

How do I add a constraint and analyze if I want to control the skew between each path through the combinational logic?

Solution

The skew cannot be controlled for the entire path using MAXSKEW, it is used only for a net. If TPSYNC is used, the delay of the path can be controlled but not available for the skew control. Therefore, manual floorplanning, adding MAXSKEW for each net, and adding aFROM/To constraint using TPSYNC are required.

However, it is not recommended to add constraints to the paths of the combinational logic. The synchronous design should be used.
AR# 38554
Date Created 12/04/2012
Last Updated 12/04/2012
Status Active
Type General Article
Tools
  • ISE Design Suite - 12.3