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VLS-XL Assign instance pin to net - automatically create net on clicked target?

caver456

For this case, we are starting with a layout mostly done in L that has pcells but has no nets at all.

In XL, when using Connectivity -> Nets -> Assign to assign an instance pin to a net, the desired target (i.e. the second thing that it prompts you to click) is a shape or another instance terminal that has no net.  In other words, "we want to connect this pin on this pcell resistor to this other simple connectivity-free piece of metal over here."  Apparently, in the Assign command, the target has to be (a shape or via on) an existing net.

While VLS does make it easy to assign a net to the target before running Assign (set the net property on the target shape/via, or add a label and Extract Layout, etc), in this case, we don't really care what VLS thinks the net name is - we just want to see the flight and drag lines.

Is there a way to have Assign automatically create an arbitrary net with a unique net name on the clicked target, which would get rid of the need to take steps to make sure the target is a net before running Assign?

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  • Marc Heise
    Hi,

    I can't understand the motivation behind doing that. It's a lot of effort to build a connectivity out of nothing in the layout space, basically negating the
    intention of Layout XL to provide semi automation and doing layout with much less effort. You may have reasons.

    Maybe it's easier and faster to manually build the schematic? Place your pins and devices ( ignore parameters to speed it up ) and wire them. Do the binding
    to the layout. If the devices are bound you can update the schematic parameters from the layout source.

    For creating nets out of thin air:
    Can you do SKILL? I can't provide a complete solution but give some pointers.

    You basically need a routine to:
    1. get the selected shape and test if there is a net allready ( shape=car(geGetSelSet()); if !shape~>nets ... )
    2. if there is no net/netTerm, you need to create a new one in the db ( net = dbCreateNet(cv "B") ; netTerm = dbCreateTerm(net net~>name "inputOutput") )
    ofcourse you have to make sure the new netname does not exist already.
    3. add the shape to the net and make it sticky ( dbAddFigToNet(shape net) shape~>lxStickyNet=t )

    Kind regards,
    Marc
Reply
  • Marc Heise
    Hi,

    I can't understand the motivation behind doing that. It's a lot of effort to build a connectivity out of nothing in the layout space, basically negating the
    intention of Layout XL to provide semi automation and doing layout with much less effort. You may have reasons.

    Maybe it's easier and faster to manually build the schematic? Place your pins and devices ( ignore parameters to speed it up ) and wire them. Do the binding
    to the layout. If the devices are bound you can update the schematic parameters from the layout source.

    For creating nets out of thin air:
    Can you do SKILL? I can't provide a complete solution but give some pointers.

    You basically need a routine to:
    1. get the selected shape and test if there is a net allready ( shape=car(geGetSelSet()); if !shape~>nets ... )
    2. if there is no net/netTerm, you need to create a new one in the db ( net = dbCreateNet(cv "B") ; netTerm = dbCreateTerm(net net~>name "inputOutput") )
    ofcourse you have to make sure the new netname does not exist already.
    3. add the shape to the net and make it sticky ( dbAddFigToNet(shape net) shape~>lxStickyNet=t )

    Kind regards,
    Marc
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