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Altera_Forum's avatar
Altera_Forum
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17 years ago

how to use the TimeQuest to constrain the clock skew

In the Classic Timing Analyzer,these is a constrain named "Maximum Clock Arrival Skew",but it is not supported in the Quartus II TimeQuest Timing Analyzer,how to i do to constrain the clock skew in the Timequest?

THX!

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    17 years ago

    The SDC command for clock skew is 

    
set_clock_uncertainty <your_uncertainty> <clock>

    I might have the syntax wrong, but that's the name of the command.

    You can add this to the sdc file that timequest generates, then next time you open timequest and it reads the file it will load the setting.
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    17 years ago

    --- Quote Start ---

    The SDC command for clock skew is 

    
set_clock_uncertainty <your_uncertainty> <clock>
    I might have the syntax wrong, but that's the name of the command.

    You can add this to the sdc file that timequest generates, then next time you open timequest and it reads the file it will load the setting.

    --- Quote End ---

    i will try it,thank a lot!
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    17 years ago

    While some causes of clock skew can add to clock uncertainty, set_clock_uncertainty is not a command to constrain clock skew. The on-line help page for the command does mention skew, but what the command actually does is tell TimeQuest how far the clock edge can move away from the ideal position (for example, a clock edge moving around because of jitter).