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Setting a custom routing grid in Virtuoso using constraints

Juerg

Hi,

I would like to place and route some fully custom-made logic cells using Virtuoso XL (menu Route->Automatic Routing). The logic cells are made for a routing grid which is not the same as the routing grid defined in the tech file (constraint group LEFDefaultRouteSpec).

In the constraints editor/process rule editor, I have tried to define my own constraints ("Horizontal/Vertical Offset/Pitch") for each routing layer, as well as "Default Horizontal/Vertical Routing Offset/Pitch", assuming that these settings would override the defaults taken from the tech file.

However, the router does not seem to take my settings into account. Also, the routing grids which are initialized within the P/R Boundary when I choose "Reinitialize Floorplan" always show the settings from the LEFDefaultRouteSpec constraint group while ignoring my custom settings.

Is there anything that I'm missing, or is there a better way to achieve what I want? I'm not the only designer working on this project, so I cannot modify the tech file.

I'm using Virtuoso Layout Suite XL ICADV12.1-64b.500.9EHF-1270.


Thanks & best regards,

Juerg

  • Hi Juerg,

    The first thing to do is check your settings in the "Use Grid" section of the routing form.

    The default is "Manufacturing". You need to set it to "Routing"

     

    Colin

  • Hi Colin,

    Thanks for your answer. I forgot to mention, I've already set "Use Grid" to "Routing".

    In the same form, I've also tried setting "Default Constraint Group" to my custom constraint group with my grid and offset settings. However, this didn't seem to have any influence on the outcome either.


    Best regards,

    Juerg

  • Hi Juerg,

    Can you try using the Wire Assistant GUI instead.

    Try this:

    Under options->editor. In the "Wire Editing" section select your Constraint Group with the new Grid definitions

    In the Wire Assistant, select "snap wires to: routing grid.

    Under the section "Automatic" click "route Net: All

    You may see some different results.

    If so, let us know.

    Going forward, this is the preferred way to run the autorouter. The router GUI is no longer being enhanced and may be removed in a future release.

     

     

    Regards

     

    Colin

  • Hi Colin,

    Thanks again four your advice!

    Your suggestions seem to do the trick, so using the Wire Assistant GUI is the way to go (at least in my case...).

    Best regards,

    Juerg

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