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how to fix transition on excluded net?

dota

In encounter, optDesign -drv can help us fix transition, but some nets are excluded. how to report those net? If I want to fix some transition on excluded net, how to do?

ps: sometimes optDesign -selectedNets can help me to fix some excluded net, but sometimes not.

 

Dota

Parents

  • Thanks for the follow-up.

    As you work with these clock nets, it would be good to understand whether the nets in question clock nets from a timing perspective -or- from a CTS perspective.  The following blog post might be informative in this area:

    http://www.cadence.com/Community/blogs/di/archive/2008/08/20/understanding-clock-net-markings-in-soc-encounter.aspx?postID=10803

    There is a native command that is targeted at fixing the CTS clock nets that have DRVs remaining because they've been excluded (which happens most typically because of an ExcludePin statement in the clock tree spec file): "fixClockExcludedNetDRV".  I'm not sure whether it would be helpful in your case- it depends on why your nets are being excluded.

    It seems like reportIgnoredNets should report clock nets as being ignored.  I just tried a small testcase and I see some clock nets being caught:

    56 IO nets
    6 clock nets
    179 special nets
    1 no-driver net 

    There might be a bug in reportIgnoredNets in your case- though it is hard to tell for certain without looking at the data.  If you feel there is a bug, I'd encourage you to follow-up with your local support AE or by filing a service request on http://sourcelink.cadence.com.

    Great discussion!  Thanks for taking the time.

    Regards,
    Bob

     

Reply

  • Thanks for the follow-up.

    As you work with these clock nets, it would be good to understand whether the nets in question clock nets from a timing perspective -or- from a CTS perspective.  The following blog post might be informative in this area:

    http://www.cadence.com/Community/blogs/di/archive/2008/08/20/understanding-clock-net-markings-in-soc-encounter.aspx?postID=10803

    There is a native command that is targeted at fixing the CTS clock nets that have DRVs remaining because they've been excluded (which happens most typically because of an ExcludePin statement in the clock tree spec file): "fixClockExcludedNetDRV".  I'm not sure whether it would be helpful in your case- it depends on why your nets are being excluded.

    It seems like reportIgnoredNets should report clock nets as being ignored.  I just tried a small testcase and I see some clock nets being caught:

    56 IO nets
    6 clock nets
    179 special nets
    1 no-driver net 

    There might be a bug in reportIgnoredNets in your case- though it is hard to tell for certain without looking at the data.  If you feel there is a bug, I'd encourage you to follow-up with your local support AE or by filing a service request on http://sourcelink.cadence.com.

    Great discussion!  Thanks for taking the time.

    Regards,
    Bob

     

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