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Altera_Forum's avatar
Altera_Forum
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9 years ago

Is this metastability or is this Signaltap behaviour normal?

Hi there I am experiencing strange behaviour from SignalTap. Occasionally, when I read data, the data return seems garbled and impossible. The values are strange for the registers from which th...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
9 years ago

Are you clocking it in the correct domain? That's the most common one. (Naturally, if it's not toggling at all then it doesn't matter what domain.) The other possibility I can think of is the stp domain is not meeting timing. Very unlikely though, as it's very simple logic. I don't think I've ever seen it fail.

One other thing is to duplicate some of the registers in our logic(and put an attribute on not to remove fanout free registers), then tap those too and see if they match. Just a thought.