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About GCELLGRID and TRACK Statement in DEF

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How are the parameters for following statements used in DEF file calculated GCELLGRID TRACK For example, in a DEF file, statements appear as: TRACKS Y 500 DO 146 STEP 1000 LAYER metal1 ; GCELLGRID Y -50 DO 2 STEP 9950 ; GCELLGRID X 173250 DO 1 STEP 7450 ; How are the parameters for these statements calculated. GCELLGRID and TRACK are two of the statements which are used to define the floorplan for a particular design. But, how are the values for these statements calculated? Thanks.


Originally posted in cdnusers.org by johariph
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  • I believe they are calculated based on the floorplan size and the routing metal definitions in the LEF. For example, TRACKS Y 500 DO 146 STEP 1000 LAYER metal1:

    This means put metal1 tracks horizontally (stepping along the Y axis) starting at 500. Put down 146 of them, 1000 apart. FE knows how many to put down (146) based on the size of your floorplan. It knows the spacing (1000) from the width and spacing of metal1 in the LEF. It knows the starting coordinate (500) based on where your floorplan starts and whether or not you start with half-track offset (looks like you do here).

    GCELLGRID numbers are also automatic, and meant to create a "box" encompassing a certain number of horizontal and vertical tracks. The tool tunes this automatically and we never really mess with it.

    Not sure that answers your question, but hope it helps somewhat.

    - Kari


    Originally posted in cdnusers.org by Kari
Reply

  • I believe they are calculated based on the floorplan size and the routing metal definitions in the LEF. For example, TRACKS Y 500 DO 146 STEP 1000 LAYER metal1:

    This means put metal1 tracks horizontally (stepping along the Y axis) starting at 500. Put down 146 of them, 1000 apart. FE knows how many to put down (146) based on the size of your floorplan. It knows the spacing (1000) from the width and spacing of metal1 in the LEF. It knows the starting coordinate (500) based on where your floorplan starts and whether or not you start with half-track offset (looks like you do here).

    GCELLGRID numbers are also automatic, and meant to create a "box" encompassing a certain number of horizontal and vertical tracks. The tool tunes this automatically and we never really mess with it.

    Not sure that answers your question, but hope it helps somewhat.

    - Kari


    Originally posted in cdnusers.org by Kari
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