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AR# 32027

10.1 MAP - External feedback from my DCM issues the following message when ODDR generates the forwarded clock, "WARNING:PhysDesignRules:1236"


I am using a DCM with external feedback. The output feedback clock is generated with the ODDR clock forwarding scheme. I have included the appropriate FEEDBACK constraint on the forwarded clock on the DCM and I still get the following warning during MAP:

"WARNING:PhysDesignRules:1236 - Unknown DCM_ADV feedback loop"

What does the warning mean?


This warning can be safely ignored and timing will be analyzed properly. A CR has been filed to investigate this issue and correct the message.

AR# 32027
Date Created 06/15/2009
Last Updated 12/15/2012
Status Active
Type General Article