Timothy Miller wrote:

> This sync fifo is intended to handle cases where there is no fixed
> relationship between the two clock domains.  For instance, PCI might
> be at 33.333MHz and the other end of the FIFO might be going at
> 200MHz, but those are just approximate, and the clock generators are
> completely unrelated.  That means there will be drift and jitter
> between them that will make the clock edges occur too close on a
> regular enough basis.

Oops, sorry, on the projects I've worked on a 'sync FIFO' has been
synchronous in that both ends are clocked from the same clock -- so I had
the wrong end of the stick.

> I'm also being conservative because although I have some sense of
> what'll happen if the signals are register-to-register, I have no idea
> what will happen if you put combinatorial logic in between them.  I
> think I'll just not take the risk.

Yes, in this case I most certainly _would_ add an extra register in for
safety's sake, and suffer the small latency penalty.

Peter


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