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Kaz, do you mind elaborating more on this part as I am not familiar how I/O timing works with regards to tSU/tH/tCO. Does that mean fitter will randomly assign some values for those if unconstrained?
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yes it will as it inserts delays freely.
If it was me I will issue warning (or error) and stop compilation. However some designers prefer to close timing in three stages:
1) do internal paths only
2) add io
3) adding exceptions
the easiest is first and must pass before moving on.
I personally put it all in one go.
The tSU/tH achieved at inputs and tCO at outputs will be reported under device datasheet.
Honored Contributor
