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 clockRouting, selectNet -allDefClock cannot find any clock 

Last post Wed, Dec 11 2013 12:41 AM by marten. 4 replies.
Started by marten 05 Dec 2013 02:20 AM. Topic has 4 replies and 4502 views
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  • Thu, Dec 5 2013 2:20 AM

    • marten
    • Top 500 Contributor
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    • Bielefeld, Nrth Rhine Westfalia
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    clockRouting, selectNet -allDefClock cannot find any clock Reply

    Hi there,

     as the subject says,

     selectNet -allDefCloc

    is not able to find any clock nets:

     " **WARN: (ENCSYC-1188):  Cannot select clock net - could not find it."

     Although, I ran CTS in advance:

      ckSynthesis -forceReconvergent -rguide par_$Utilisation/ctgen/$Entity.guide -report par_$Utilisation/reports/$Entity.ctsrpt
      createClockTreeSpec -output par_$Utilisation/$Entity.ctstch\  -bufferList $CT_BUFFER
      specifyClockTree -file par_$Utilisation/$Entity.ctstch

      createSaveDir par_$Utilisation/ctgen
      ckSynthesis -forceReconvergent -rguide par_$Utilisation/ctgen/$Entity.guide -report par_$Utilisation/reports/$Entity.ctsrpt
      saveClockNets -output par_$Utilisation/ctgen/$Entity.ctsntf
      saveNetlist par_$Utilisation/ctgen/$Entity.v
      savePlace par_$Utilisation/ctgen/$Entity.place

     

    I would be glad about any hints what to do.


    Cheers,

    Marten

     

    • Post Points: 20
  • Fri, Dec 6 2013 6:03 AM

    • BobD
    • Top 25 Contributor
    • Joined on Fri, Jul 11 2008
    • Chelmsford, MA
    • Posts 247
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    Re: clockRouting, selectNet -allDefClock cannot find any clock Reply

    Hi Marten,

    It sounds like the clock net markings are getting purged from the database somehow. Try triaging it by querying the "isCTSClock" attribute on all the nets in the design after each step in your flow to see where they're getting removed:

    encounter 11> dbGet top.nets.isCTSClock
    1 1 1 0 0 0 

    I think you'll find that either tracing is malfunctioning somehow -or- some downstream command you're using before selectNet is purging the markings. Let us know if you find the problem and we'll get it repaired! 

    Hope this helps,
    Bob

    • Post Points: 20
  • Tue, Dec 10 2013 8:16 AM

    • marten
    • Top 500 Contributor
    • Joined on Thu, Aug 8 2013
    • Bielefeld, Nrth Rhine Westfalia
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    Re: clockRouting, selectNet -allDefClock cannot find any clock Reply

     Hi Bob,

     thanks for your reply.I think the clock tree specification is not right because when I try to build the clock tree using

     ckSynthesis -forceReconvergent -clk clk -rguide par_0.5/ctgen/entity.guide -report par_0.5/reports/entity.ctsrpt

     I get the following error:

     **ERROR: (ENCCK-725):
     The BufMaxTran 0.3 (ps) in the clock tree specification file for AutoCTSRootPin clk is too small to synthesize any valid clock.

    Which value do I have to use for "BufMaxTran" ? I am not sure what this variable means.

    My netlist was synthesized with 100 ns.

     

    Cheers,

    Marten 

     

    • Post Points: 20
  • Tue, Dec 10 2013 8:22 AM

    • BobD
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    • Chelmsford, MA
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    Re: clockRouting, selectNet -allDefClock cannot find any clock Reply

    BufMaxTran is the target transition time you're asking the tool to achieve on buffers in the clock tree. You probably don't want 0.3ps. You probably want 0.3ns. Try supply the units (ns) in your clock tree spec file where 0.3 is specified for BufMaxTran. If you're not specifying this value and it's defaulting to that try specifying it to 0.3ns.

    Hope this helps,
    Bob 

    • Post Points: 20
  • Wed, Dec 11 2013 12:41 AM

    • marten
    • Top 500 Contributor
    • Joined on Thu, Aug 8 2013
    • Bielefeld, Nrth Rhine Westfalia
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    Re: clockRouting, selectNet -allDefClock cannot find any clock Reply

     Thanks Bob, it is working now!

    • Post Points: 5
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Started by marten at 05 Dec 2013 02:20 AM. Topic has 4 replies.