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Editing CDF parameter properties for a Pcell

ahamlett

 The only documentation on this I have found is from Cadence Design Framework II SKILL Functions Reference (skdref.pdf) on page 698:

Attribute     Set?  Type   Description

valueType   no     string  The type of the value of this property:
                                     “boolean” Boolean
                                     “fileName” file name string
                                     “float” Floating-point integer
                                     “hierProp” Property list
                                     “ILExpr” IL expression string
                                     “ILList” IL list
                                     “int” Integer
                                     “NLPExpr” NLP expression string
                                     “string” String
                                     “time” Time-valued string

I want to be able to force the display name or prompt of pcell parameters by editing the pcell's base cdf:

cdfCreateParam(cdfCreateBaseCellCDF(ddGetObj(libName cellName))
    ?name            "myParam"
    ?prompt          "My Param's Prompt"
    ?defValue        car(layerList)
    ?type              "ILList"
    ?storeDefault    "yes"
)

However I keep getting this error when loading the pcell:

*Error* icGetCurrentWindow: invalid cdf parameter type - "ILList"

I've tried ilList and ILList as the parameter type. Why isn't this working?

 BTW, what does CDF stand for? Cadence Design Framework, Cell Database Function, etc?

Edit: Found out what CDF stands for... Component Description Format.

Also, I am trying to change the value of parameters on the instance of a pcell... anyone know how to do that?
I would need to know the object of the parent which instances the pcell.

  • I think CDF stands for "Component Description Format".

    You have a legitimate question that we have been asking Cadence for years. The short answer is that CDFs do not support "lists" even though Skill is a "list-based" language. You will have to convert your value to a string and complain to Cadence to finally fix this painful limitation on CDFs.

    -Derek

  • Hi Alan,

    Derek is correct on multiple counts - CDF is an acronym for Component Description Format.

    Unfortunately PCells do not support the use of a list CDF parameter type. 

    See my solution on supported CDF parameter typesfor PCells on Sourcelink: SourceLink Solution 11130422

    I found a CCR (well, a PCR) request for this dating back to 1996!

    The solution is, as Derek mentioned, to convert the list to a string and back again inside the PCell.

    Best regards,

    Lawrence.

  • I'm presuming that you wish to know the parent from within the PCell code?  In the past when I wanted to know the cell that instantiated a PCell I used a parameter on the PCell that stored the parent cellview's name. It's ugly, but a cell does not normally know where it is instantiated, and things are more complex for PCells, so I gave up searching for a more elegant solution (if one even exists).

    Regards,

    Lawrence.

  •  Since the virtual memory database only stores a single copy of the variant master during an editing session and that master is determined by the value of the parameters on the instance, passing the master dbId as a parameter value is the only way to guarantee the correct information going into the pcell. You can pick up the current cellView in the editor using SKILL but the first time the pcell is instantiated, that value for the cellView is fixed and does not change even if you instantiate the pcell with the same parameter values in another cell. This may create bad data for anything dependent on the top level cell. Also, processing outside the editor (such as generating Stream format) may cause such a pcell to fail. So, if you need the master of your pcell instance, you need to pass that value in as a parameter.

     Ted

  • Thanks for all the helpful replies.
    I already have the list pcell parameter imported as a string... I was just hoping for a built-in or more robust way.

    The reason for wanting a pcell to be able to change its own instance parameters instead of only being able to change it's default parameters was to make it more user-friendly by updating parameter values, but having the user enter the pcell's instance information kindof defeats that purpose.
    Thanks again for all the help and hopefully Cadence improves the CDF to accept lists as parameters.

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