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AR# 7852

Virtex CLKDLL - How do I make sure the DONE does not go high until the CLKDLL has been locked?


DONE pin indicates that the configuration process is over, and the device is in the Startup sequence. By default, the configuration startup sequence does not wait until the CLKDLLs have locked. How do I make sure the DONE does not go high until all the CLKDLLs are locked?


This is a two-step process:

1. Attach the STARTUP_WAIT attribute to the CLKDLL in the ucf file


2. Use the following option in bitgen program:

-g LCK_cycle:#

Where # is a number between 0-6

To set the -g LCK_cycle:# in the GUI go to

Implementation -> Options -> Edit Configutaion Options -> Startup Tab

then click "C#" in the Release DLL section.

AR# 7852
Date Created 08/21/2007
Last Updated 12/15/2012
Status Active
Type General Article