Forum Discussion
Hello, In my design I keep getting hold time violation warnings. "From Node" and "To Node" in the TimeQuest indicate the same signal.
Most of the signals relate to NIOS. The design based on a single 100MHz clock. There is an additional clock 12.5MHz generated in pll in QSYS and connected only to epcs flash controller. I've seen similar connection of the epcs flash controller in some examples.
I get no setup time violations and functionally everything works fine. But I can't get rid of hold time violation warnings. See the attached TimeQuest Report. Please help.
Thank you.
21 Replies
- ACoga
New Contributor
Hi @KhaiY_Intel ,
No, most of the warnings relate to Altera IP code such as FIFO, EPCS controller, NIOS, so I can't change the design.
Thank you.
- KhaiChein_Y_Intel
Regular Contributor
Hi Hi ACoga,
Do you mind to share the design?
Thanks
- ACoga
New Contributor
It's possible. How can I do it?
- KhaiChein_Y_Intel
Regular Contributor
Hi ACoga, You may attach in this thread. Thanks - KhaiChein_Y_Intel
Regular Contributor
Hi ACoga, Any updates? Thanks - ACoga
New Contributor
Hi YY,
Unfortunately, I have restrictions to share the design...
Do you have any ideas what can I check to get rid of these warnings?
Thank you.
- KhaiChein_Y_Intel
Regular Contributor
Hi, You may try to overconstrain the path. https://fpgawiki.intel.com/wiki/Timing_Constraints#Overconstrain_path Thanks. - ACoga
New Contributor
Thank you very much @KhaiY_Intel , great explanations. I'll try to overconstrain, but it looks that I have a problem with some settings. The warnings don't look real - all of them from and to the same node...
- KhaiChein_Y_Intel
Regular Contributor
Hi, Do you have any updates? Thanks. - ACoga
New Contributor
Hi @KhaiY_Intel ,
I haven't solved it yet. Not really clear how to overconstrain the hold warnings of the same clock To and From the same signal. The number of the warnings (I could see a few hundreds of them and don't know the exact number - could be much higher) makes me think that something basic is wrong.
I've tried to remove the .sdc file and leave only derive_pll_clocks, but this type of warnings still appears, so it is not the .sdc file issue.
I'm working with Quartus 16.1, someone advised me to try a newer version. I can try it on the next week.
If you have any new ideas, I'll appreciate it.
Thank you.