AR# 12655

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

Description

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.

Solution

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

documentation.

AR# 12655
Date 01/18/2010
Status Archive
Type General Article
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