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AR# 36891

Virtex-5 DCM DRP - Why does the DCM sometimes not regain LOCK when I change the M and D values via DRP?

Description

Why does the DCM sometimes not regain LOCK when I change the M and D values via DRP?

Solution


When performing any DRP interactions (either reading or writing) you need to ensure that you read from address 00H at the end, this ensures that the DCM re-locks correctly as it restores the default DCM status output.

The user guide is going to be updated to include this requirement for both reading and writing from the DRP (it currently only mentions reading).

After a DRP access either read or write, a read from address 00h must be issued. This read restores the default DCM status output.

Another cause of would be if the user change the DCM frequency mode to outside the correct range.
AR# 36891
Date Created 07/20/2010
Last Updated 12/20/2010
Status Active
Type General Article
Devices
  • Virtex-5 FXT
  • Virtex-5 LX
  • Virtex-5 LXT
  • More
  • Virtex-5 SXT
  • Virtex-5 TXT
  • Virtex-5Q
  • Virtex-5QV
  • Less