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harnhua's avatar
harnhua
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3 years ago

How to count levels of logic in timing paths?

Hi, I am having some trouble finding out where the levels of logic are in my critical paths on a Stratix10 design in Quartus Prime 21.4 Pro Edition. For example, in Timequest, the Statistics show...
sstrell's avatar
sstrell
Icon for Super Contributor rankSuper Contributor
3 years ago

That is strange. Like you say, normally logic levels are counted as jumps between cell delays and interconnect delays. Maybe it's because this is inside encrypted IP. Do you see multiple paths like this? Or paths that do display the number of logic levels correctly?

harnhua's avatar
harnhua
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3 years ago

Yes, I see multiple paths like this.

So far, all the paths with incorrect logic level numbers seem to belong to encrypted IP.

And yes, I do see paths with the correct number of logic levels. The one shown below makes sense that it has 2 logic levels.

Interestingly, those are located in unencrypted nodes. I am able to view and verify the logic levels in the schematic view as well.

I guess there may be a bug (or intended feature) in the path statistics for paths in encrypted IP?

Thanks