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Streaming out pcells to gds

mtwadeCU

Hi,

While I'm actively developing a pcell, it is useful to be able to stream out a gds directly from the pcell without instantiating it in another layout first. However, when I try to stream out the pcell using the CIW File -> Export -> Stream, the streamed out file is empty and the "Summary of Objects Translated" message to the CIW shows that zero shapes were translated. If I first create a new layout cellview and instantiate the pcell in that layout, I can stream things out just fine. Is there a way to stream out a pcell without first instantiating it in a larger layout? 

Thanks,

Mark 

  • Andrew Beckett

    Mark,

    Not sure which version you're using, but I just tried this in IC616 (ISR7, as it happens) and it works fine.

    It might slightly depend on how you're developing the pcell too (if you're using pcDefinePCell rather than dbDefineProc) because it will not evaluate the pcell as such, but use whatever default shapes are in the pcell (which for  pcDefinePCell would correspond to whatever the default values produced).

    Regards,

    Andrew.

  • mtwadeCU
    Andrew, Thanks for the quick response. I'm using 6.1.6, and using pcDefinePCell to create the pcells. I've successfully done what I'm describing on a different Cadence install at a previous institution, so I know it can be done (as you just tested yourself). I'm now just looking for any reason that it doesn't work on the Cadence install I'm currently using. Any ideas? Mark
  • Andrew Beckett

    Mark,

    Did the pcells get saved? Perhaps you need a dbSave of the  to ensure it's on disk as the stream out is a background process. Or you could try streaming out from VM ( a choice on the stream out form)

    Andrew 

  • mtwadeCU

    Yes, the pcells are saved. I also tried streaming out from VM, and it didn't work.

    Mark 

  • Andrew Beckett

    Mark,

    I'll put together a small example (not today as it's after 10pm here) to check that it works with a newly created Pcell and then post it here for comparison purposes.

    Regards,

    Andrew 

  • mtwadeCU

    Andrew,

    Great -- thanks for the help!

    Mark 

  • mtwadeCU

    Another clue: I found that streaming out without instantiating works on version 6.1.5. However, we can't use 6.1.5 due to its inability to handle size operations on polygons larger than 4000 points. The exact versions are: 

    IC6.1.5.500 (works)
    IC6.1.6.101 (does not work)

    As a workaround, we're using 6.1.5 for streaming out and 6.1.6 for our polygon operations, but it's kind of a pain.


    Mark 

  • Andrew Beckett

    Mark,

    I've tried streaming out from VM works in all IC616 subversions (base release, plus ISR1 to ISR7). However, I found that adding a dbSave() wasn't enough to make it work without save from VM. I also had to do a "make readonly" (in essence):

     cv=pcDefinePCell(
        list(ddGetObj("example") "example" "layout")
        (
            (w 1.0)
            (l 1.0)
            (repeatX 10)
            (repeatY 5)
            (spacing 0.5)
            (layer "Metal1")
        )
        let((x y)
            for(i 1 repeatX
                for(j 1 repeatY
                    x=(i-1)*(w+spacing)
                    y=(j-1)*(l+spacing)
                    dbCreateRect(pcCellView layer list(x:y x+w:y+l))
                )
            )
        )
    )
    dbSave(cv)
    ; need this for some reason to allow stream out from disk!
    dbReopen(cv "r")

    In IC615 this last line wasn't necessary.

    Also in IC616 (all versions that I tried), it seemed to be outputting 100 rectangles rather than 50. As far as I can see, it has two copies of each rectangle in the stream file.

    Something odd going on here...

    If you can send me a private message to say what organisation you work for, I can log this as a CCR on your behalf. At the very least you've got a workaround of being able to do the dbReopen.

    Regards,

    Andrew.

  • lkphoto
    Andrew,
    Your example works to me when slightly modified, and I get the correct number of shapes.
    When I try it in its original form, I get the same failure as before: no shapes are streamed out. I am using IC6.1.6.101.
    Streaming out a pCell did not work either with 6.1.4.xxx (where xxx = 500.10 probably). But I agree that works fine with IC6.1.5.500, which has been of great help.

    However, if I place the dbSave and dbReopen inside the pcDefinePCell definition like this:

    pcDefinePCell(
        list(ddGetObj("example") "example" "layout")
        (
            (w 1.0)
            (l 1.0)
            (repeatX 10)
            (repeatY 5)
            (spacing 0.5)
        )
        let((x y)
            for(i 1 repeatX
                for(j 1 repeatY
                    x=(i-1)*(w+spacing)
                    y=(j-1)*(l+spacing)
                    dbCreateRect(pcCellView list("rx" "drawing") list(x:y x+w:y+l))
                )
            )
        )
        dbSave(pcCellView)
        dbReopen(pcCellView "r")   
    )

    then it works and exports only 50 rectangles as it should (if I counted them right) and 1 Cell.

    I also get these printed in CIW:
    Generating Pcell for 'example layout'.
    *WARNING* (DB-270000): dbMakeParamCell: Cannot modify a read-only design
    *WARNING* (DB-270000): dbSave: Attempt to save a read-only design
    *WARNING* Can't save superMaster.
    nil

    Kind regards,
    lkphoto
  • Andrew Beckett

    Ikphoto,

    Adding save statements inside the pcell code makes no sense, because you can't save the subMaster (which is what you're attempting to do) - which is why you're getting the warnings. I suspect it's the readonly that is making it work.

    In my case visually looking at it I could see 50 rectangles, but there were in fact two sets on top of each other.

    I'll be filing CCRs for this today.

    Regards,

    Andrew.

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