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AR# 13110

4.1i Timing Analyzer/TRCE - Cross-clock paths ending at DCM phase shift pins are not analyzed

Description

General Description:

A path starting with one clock is not analyzed by a period constraint when the endpoint is a phase shift pin of the DCM (such as PSINCDEC). The two clocks are related, and using a FROM:TO constraint on the two clock groups does not work. How do I constrain these paths?

Solution

To work around this problem, use a TPSYNC on the DCM pin in a FROM:TO constraint as follows:

NET "clka" TNM_NET = "clka";

PIN dcm_name.PSINCDEC TPSYNC = "syncpoint";

TIMESPEC "TS_crosssync" = FROM "clka" TO "syncpoint" 20 ns;

AR# 13110
Date Created 08/29/2007
Last Updated 01/18/2010
Status Archive
Type General Article