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 PnR tips, macros placement 

Last post Sat, Oct 5 2013 3:35 AM by Kirtesh Tiwari. 4 replies.
Started by vincentcold 26 Jul 2013 04:22 PM. Topic has 4 replies and 4235 views
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  • Fri, Jul 26 2013 4:22 PM

    PnR tips, macros placement Reply

    Hi !

          I'm new to floorplanning, and PnR in industry level. Can someone please help me with some tips from your experience, and where to find useful examples for macros placement, some kind of things you do to prevent congestion, and make your design more robust. Thanks a lot ! 

    • Post Points: 20
  • Mon, Aug 12 2013 10:48 AM

    • fitz
    • Top 150 Contributor
    • Joined on Wed, Aug 4 2010
    • Kanata, Ontario
    • Posts 56
    • Points 745
    Re: PnR tips, macros placement Reply

    Unfortunately the answer is "It depends".
    If you are intimate with the circuit you should be able to anticipate the module guide and hence the macro placement based on your knowledge of the data flow.

    If the circuit is completely foreign,  you have a lot of research ahead of you.
    Just to get a plausible start point I generally begin with the EDI automatic floorplan commands planDesign , setPlanDesignMode  and multiPlanDesign.
    Good documentation under  / doc / soceUG / Creating An Initial Floorplan Using Automatic Floorplan Synthesis.html.
    You will notice that planDesign generally places macros toward the periphery, a valid technique because it leaves the central core area free for standard cells.

    If you have hundreds of macros you are going to need the relative floorplan menu "define array constraints"  to simplify your macro positioning.

    The overall strategy  also depends on how many routing layers you have to get over top the macros, if you are forced to go around, congestion is going to be problem.
    The fewer the number of routing layers the closer to the edge they belong.
    With 8-10 interconnect layers your options open up,  IF the macro connected standard cells naturally gravitate toward the center the associated macro  can also be drawn closer to the center .

    It Is going to take time to get right.
    Another trick of the trade is to use trialRoute -noDetour  during your floor planning exercise, if you can solve the congestion problem with low effort routing the final route is going to be easy.

    Shawn

    • Post Points: 20
  • Mon, Aug 19 2013 10:53 AM

    Re: PnR tips, macros placement Reply
    Thank you so much Shawn ! you're awesome. Those tips are really helpful, I have tried them out and I start to get the hang of it. I just needed something to start with. 
    • Post Points: 20
  • Fri, Sep 20 2013 1:28 PM

    • Kari
    • Top 10 Contributor
    • Joined on Tue, Jul 15 2008
    • Cary, NC
    • Posts 695
    • Points 14,420
    Re: PnR tips, macros placement Reply
    I agree, that was an excellent post! Thanks for contributing to the forums, Shawn! :-)
    • Post Points: 20
  • Sat, Oct 5 2013 3:35 AM

    • Kirtesh Tiwari
    • Not Ranked
    • Joined on Mon, Apr 23 2012
    • unnao, Uttar Pradesh
    • Posts 6
    • Points 90
    Re: PnR tips, macros placement Reply
    lovely , awesome :-) Shawn
    • Post Points: 5
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Started by vincentcold at 26 Jul 2013 04:22 PM. Topic has 4 replies.