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Why is a crosstalk table needed for a basic fast autoroute

tmd63

When attempting to use the autoroute feature in Allegro PCB Editor (design.brd not design.dsn file). The router refuses to run unless a cross-talk simulation is run first.

I just want a simple x-y autoroute done using specific layers where layer 8 is the x direction and layer 10 is the Y direction (for example). I have over 4,000 connections to complete in 4 hours and it is too much for my mouse/fingers/brain to do manually. But the simulation is taking forever to run and will provide no useful help as there are no impedance requirements on the PCB!

So how can I run a simple Autoroute to remove the majority of the simple connections (I have already fanned out most of the connections manually)? Or does Allegro not allow for autorouting any more?

  • redwire

    Hmmm....something is setup wrong.  If you pass the autorouter a constraint and you have the correct license it will follow the rules.   Not sure why you are seeing the crosstalk analysis come up first.  You might try switching your Allegro license down to the base license and try again.

    Otherwise export the autorouter "DSN" file and start the autorouter from the command line and then read in the DSN file.  Hopefully you know the standard setup commands that you need to do before kicking it off?  You will need to set the rules and then start the route.

  • tmd63
    in reply to redwire

    Thank you, but I do not have a dsn file. I am using Allegro 17.4 and it has a .brd file instead. I am not using OrCAD.

  • DavidJHutchins

    From a command line window try the following commands

    spif_batch design.brd design.dsn

    specctra design.dsn

  • tmd63
    in reply to DavidJHutchins

    But David, I do not have Specctra or Design.dsn files. My design is a design.brd!!

  • DavidJHutchins

    When you use Route>PCB Router from within Allegro it's actually invoking specctra.exe

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