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Knug's avatar
Knug
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4 years ago

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

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 ?

2 Replies

  • RichardT_altera's avatar
    RichardT_altera
    Icon for Super Contributor rankSuper Contributor
    4 years ago

    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_com_check_timing.htm

    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.

  • RichardT_altera's avatar
    RichardT_altera
    Icon for Super Contributor rankSuper Contributor
    4 years ago

    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.