virtex-II DCM phase shift problems

I have the same problem using my spartan3. Have you solve your proble yet?

thanks

Something I saw in my own design: the state machine I was using to control the DCM in my Spartan-3E issued a PSEN before the DCM was ready. Since the state machine was waiting for a PSEN that would never come, my initial reaction was that I never received the PSDONE.

By adding an explicit timeout for the PSDONE to reissue a PSEN as a workaround in my initial code, I was able to issue a first PSEN as seen by the DCM.

Only with this timeout in place did I find that sometimes - making 10s of thousands of adjustments - the time from PSEN to PSDONE would exceed even the 5x timeout period I had designed for on very rare occasions.

If you design a state machine to deal with a timeout, I'd suggest disabling the timeout after the first PSDONE is detected. If you're getting an error because you find yourself waiting too long, wait longer. If you're in this latter camp, it might be helpful to record a histogram of how many clock cycles it takes between PSEN and PSDONE. For your specific input jitter environment, you may get results that deviate from the published maximums.

- John_H

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I checked lock pin and it's locked. So, it should be ready for phas alignment. I don't know why I still couldn't get it to work. How do yo do with your reset sequence? If possible, can I take a look at your cod to see what I missed?

thanks a lot,