04-03-2009 06:02 AM
I have a design that write to a FIFO in a 166MHZ clock domain and read in a 332MHz clock domain. The clock domain are unrelated. I have a TIG constraint between these two clock domains. I am getting bit errors reading out of the FIFO. I am using first word fall through with the valid flag. I have tried implementing this FIFO using the FIFO generator using distributed RAM and block RAM. Both implementations show this problem. The timing report shows now errors.
I have other asynchronous FIFOs running at slower rates that don't show this problem. Is there a possible vulnerability in the way I am using it?
I am in the process of trying it with the built in FIFO structure.
I appreciate any insights you have.