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open01
Novice
88 Views

Timing Analyzer

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Hi,

I have two questions about Timing Analyzer.

1. As show in the fig, Quartus reminds me that I have two Unconstrained Clocks, But these two are not clock signals in my design, how can I correct them?

open01_0-1612758262132.png

2.If I have a hold violation in my project, as shown in the figure, how can I fix it?
Can I fix it by adding a delay cell? How can I add a delay cell to my data path?

open01_1-1612758580783.png

 

I appreciate your help very much.

O.Chiang

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open01
Novice
38 Views

Hi,
I know where the problem is.

Because my design accidentally synthesized a latch, and these two signals are connected to latch_en, Quartus regards these two signals as clock.
When I removed the latch, the situation was resolved.

Thank you very much for your help.

O.Chiang

View solution in original post

3 Replies
sstrell
Honored Contributor II
69 Views

You don't mention what clocks the tool is telling you are unconstrained.  What are they?  If it's the JTAG clock, look at this:

https://www.intel.com/content/altera-www/global/en_us/index/support/support-resources/knowledge-base...

As for the hold timing issue, without seeing the design or the .sdc (or even knowing what path is failing timing), this isn't really possible to solve.  It looks like you're going between two different clock domains and maybe need multicycle, but it's impossible to tell for sure.

open01
Novice
54 Views

Hi, thanks for your reply

About the first question. I mean, Quartus mistaken the signal for a clock signal, in fact he told me that the two Unconstrained signals are not a clock signal in my design. Those two signals are just normal Register output's data.

 

Regarding the second question. I found my mistake after your hint, maybe I only need to set the path to false path, thank you very much!

 

I appreciate your help very much.

O.Chiang

open01
Novice
39 Views

Hi,
I know where the problem is.

Because my design accidentally synthesized a latch, and these two signals are connected to latch_en, Quartus regards these two signals as clock.
When I removed the latch, the situation was resolved.

Thank you very much for your help.

O.Chiang

View solution in original post