FPGA Intellectual Property
PCI Express*, Networking and Connectivity, Memory Interfaces, DSP IP, and Video IP
Announcements
Intel Support hours are Monday-Fridays, 8am-5pm PST, except Holidays. Thanks to our community members who provide support during our down time or before we get to your questions. We appreciate you!

Need Forum Guidance? Click here
Search our FPGA Knowledge Articles here.
5881 Discussions

false_path issue seen in the STA tool when running 'check_timing'

Knug
Beginner
189 Views

I set false path to the following signal :

set_false_path -from [get_ports fpga_nstatus]

& when I run STA check_timing reported 'no input delay was set on the input port'

Same with other false paths I set.

I am currently ignoring this. Please comment here.

On the other hand when I select 'Report Unconstrained paths' there were no unconstrained paths reported (as expected).

Why 'check_timing' reported that message ?

 

0 Kudos
2 Replies
RichardTanSY_Intel
134 Views

Hi @Knug 

 

Sorry for the late response. 

In Check Timing, the no_input_delay check verifies that every input port that is not determined to be a clock has an input delay assignment. Thus the message reported. 

Reference: https://www.intel.com/content/www/us/en/programmable/quartushelp/current/index.htm#analyze/sta/sta_c...

 

You might have wrote a wrong sdc command thus no unconstrained paths reported. 

In the Timing Analyzer, you can set false path by clicking Constraints > Set False Path to ensure that the tool recognize the paths. 

You may checkout the user guide here on set_false_path sdc command and its example.

https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/ug/ug-qpp-scripting.pdf

 

Best Regards,
Richard Tan

p/s: If any answer from the community or Intel support are helpful, please feel free to give Kudos. 

RichardTanSY_Intel
97 Views

I have yet to receive any response from you to the previous question/reply/answer that I have provided but I believed that I have answered your question. 
With that, I will now transition this thread to community support. If you have a new question, feel free to open a new thread to get the support from Intel experts. Otherwise, the community users will continue to help you on this thread. Thank you.

Best Regards,
Richard Tan

p/s: If any answer from the community or Intel support are helpful, please feel free to give Kudos. 

Reply