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 Structured datapath (SDP) difficulties 

Last post Wed, Jun 12 2013 12:11 PM by jk123. 0 replies.
Started by jk123 12 Jun 2013 12:11 PM. Topic has 0 replies and 644 views
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  • Wed, Jun 12 2013 12:11 PM

    • jk123
    • Not Ranked
    • Joined on Mon, Apr 30 2012
    • New York, NY
    • Posts 1
    • Points 5
    Structured datapath (SDP) difficulties Reply

    I am trying to use SDP with EDI 13.11 and am running into a problem.  Hoping someone can offer some advice; my apologies for the length of this post.

    * GOAL

    Here's what I want to accomplish:

    (1) Write an sdp description suitable for reading with the readSdpFile command.  No problems here; I can do this.

    (2) Just prior to calling placeDesign, load the SDP file into encounter with readSdpFile.  Intentionally do *not* specify an origin for the SDP since I want the encounter placer to choose the best location for the SDP.

    (3) Automatically select a placement for the SDP and for the remaining cells, and run thru the usual optDesign, CTS, etc. flow all while keeping the SDP together with its cells aligned as specified in the original sdp file from step (1).

    (4) End up with a legal placement, with the SDP still together and aligned and not overlapping any existing cells.

     

    * PROBLEM

    I can't seem to get this to work.  The main problem I'm running into is with the preplaced, FIXED welltap cells in our floorplan.  If placeDesign and/or optDesign decides to place the SDP across welltap cell(s), it needs to split the SDP (while retaining cell alignment) to make room for the welltap cell(s) that would otherwise overlap some of the SDP cells.  Alas, placeDesign, refinePlace and optDesign don't seem to do this even though I'm specifying the welltap cell names in set_sdp_mode (see below).

     

    I'm attaching a screen dump that shows the SDP after placeDesign.  You can see three vertical columns of welltap cells highlighted in yellow, and you can see the SDP, highlighted in red, overlapping the top few welltap cells in the two rightmost columns.

     

     

    * QUESTIONS:

    (1) Is the placeSdpGroup command supposed to be used?  I don't want to use it because (a) it sounds as if placeDesign accomplishes the same thing; and (b) it requires specification of an origin for the SDP but I want encounter to choose where to place the SDP.

    (2) In general, what is the recommended SDP flow?  The documentation in the "Using Structured Data Paths" section of the Encounter User Guide is unclear to me. Here's what I'm currently doing pre-CTS (showing only items relevant to SDP):

        init_design

        setPlaceMode -sdpAlignment true -sdpPlace true

        set_sdp_mode -honor_alignment true  \

            -max_move_distance 3000  \    <--- HUGE so that SDP can be moved anywhere

            -resolve_overlap_column_cell WELLTAP_CELLNAME \

            -resolve_overlap_row_cell {}

        readSdpFile -file my_sdp_filename.sdp
        
        placeDesign

        setOptMode -sizeOnlyFile my_sizeonly_filename  <--- Specifies -noMoveInst for all cells in the SDP

        setSdpObjectStatus -status placed

        optDesign -preCTS

     


    • Post Points: 5
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Started by jk123 at 12 Jun 2013 12:11 PM. Topic has 0 replies.