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AR# 12655

4.1i Constraints Guide - The CLKIN_PERIOD constraint for Virtex-II does accept units and values over 32.


General Description:

Adding units to the value of the CLKIN_PERIOD constraint, as in the

Constraints Guide example, will result in an ngdbuild error:

ERROR:NgdBuild:686 - A parsing error has occurred while reading design.ucf.

Additionally, using a value over 32 for the CLKIN_PERIOD results in a bitgen error:

WARNING:Bitgen:198 - CLKIN period -xxxxx ps is less than minimum of 2000 ps.


This issue will be resolved in ISE 4.2i and addressed in the next major release's


AR# 12655
Date Created 09/24/2001
Last Updated 01/18/2010
Status Archive
Type General Article