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Schematic nets

tito80
My problem is -- I have a list of instance names within a schematic. I want to capture only internal nets that are fed by instances other than these instances to these instances (i.e. output from one non-list instance to input of one list-instance). So this is the rough algo I am following

forall nets
if (net->term != nil)
forall insterms (net->instterms) 
if (dir == input && inst == (from within list of instances))
capture=1
elsif (dir == output && inst == (NOT from within list of instances)) 
capture=1
elsif (dir == output && inst == (from within list of instances)) 
capture=0
end if

I would like to have a pointer to a detailed SKILL documentation for schematic nets. For e.g., 

1) net~>?? shows me nil for terms where I do see terminals present. 
2) A net shows me 2 instTerm objects where I do see more instance terminals.
3) The netname sometimes come up as <*7>vccpq -- I see 7 instance terminals it connects to. However, only 2 come up on querying net~>instTerms
4) Sometimes I see same net name present in whole schematic for different nets, which finally represent the same node name in netlist. However, all of these different net segmets don't show up on querying instId~>nets (i.e. all insTerms scattered here and there dont come up). 
5) What is the difference between signals and nets.

  • tweeks

    The information you seek is buried in Chapter 2 of the Virtuoso Design Environment SKILL Reference: 

        file://$CDSHOME/doc/skdfref/chap2.html#1066896

    However, even with the full documentation, digging connectivity info out of the schematic is not as easy as it could be. SKILL code needs to deal with the complications of bussed nets, iterated instances, and the complicated syntax for grouped wire names.

    I would recommend contacting your Cadence AE for help, as they have some code lying around that will get you closer to your goal. (Ask for a copy of "CCSFindSigNameConnectedToMemberOfIterInst()").

    Here are some built-ins that may aid you in your quest: 

    dbGetInstByName()
dbFindMemInstByName()
dbGetAnyInstSwitchMaster()

dbFindSigByName()
dbFindTermByName()

dbProduceMemName()

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