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AR# 36363

12.1 PlanAhead - When changing I/O attributes on a differential pair, changes are only reflected on the master

Description

When I change the attributes for the differential I/O (e.g., slew rate, IOStandard, etc.) in the PlanAhead software, the ".ucf" file that is written out only writes out the attributes for the P side.

Why is the N side of the differential pair being ignored?

Solution

This is a known issue in the PlanAhead software.When you make changes to the attributes for a differential I/O, the changes are only reflected for the P side of the differential pair (rather than the N side).

You can work around the issue by manually writing out the attributes for the N side in the ".ucf" file.

You can also leave it as it is and the implementation tools will take care of assigning location and attributes of the N side of the pair depending on the location and attributes of the P-side.

A CR is under investigation to fix the issue for a future release of thePlanAhead software.
AR# 36363
Date Created 06/23/2010
Last Updated 05/19/2012
Status Archive
Type Known Issues
Tools
  • PlanAhead - 12.1