regarding pnr flow

  1. nitin kala
    nitin kala
    Hello all,

    I am doing pnr flow for the first time. I have got few doubts regarding that.

    1. After placeOpt, if i am still getting few r2r violating paths how to decide whether to proceede to CTS or to go back to new floorplan technique or keep on playing with the setOptMode paramters or use usefulSkew ??

    2. During CTS, what to observe in clockReport and make corresponding changes in specification file ?? what should be our primary concern whgile doing CTS ?

    Please do share your other experiences as well.

    Thanks & Regards,
  2. ro9ty
    1> Usually nowadays we do not think of closing pre-route timing but still huge violations should be an alarm. Let us say you are getting 100 violations but of 0.2ns and between r2r which are by design expected to be checked. But then suppose you have a huge timing violation coming from a reset signal or a register supposed to produce an interrupt. These special signals are expected to take more than one cycles and hence should not be checked. (Usually taken care in design) What you can see is that you should not get unusual timing violations between expected flops. In that case you would have to think of improving your placement and if that seems completely impossible due to congestion and restricted area then you will have to do the floorplan again.
    2> Look for the CTS buffer levels. It should not very high or else the skew would be huge and we all know more the skew the less dependable the design especially from timing perspective.
  3. cyrax747

    I have started in soc encounter dtmf block pnr and following the lab .The problem is i am unable to address the issues .I need complete explanation what step to perform and what errors to fix ?? how could i do that ?? the lab work is exclusively using gui its like fun play typing command and seeing the result.I need to address floorplanning issues placement issue congestion at this point of time.Can some one help me regarding this ??
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