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Unable to Route gridless in 17.2

tmd63

I have basic grids set as 0.1mm in a 17.2 design, but need some routes on a different grid. When I select gridless routing, the rout still snaps to the grid!

How do I route gridless when selecting gridless refuses to work. (The routes needed are on a 15thou trace with 15thou spacings for a flexi!)

But the design is a metric system design, with only a small area requiring imperial spacings.

  • excellon1

    Gridless is only used for pushing obstacles out of the way, for example while routing a trace next to a via the via will be pushed away but not snap to a grid.

    Traces snap to a grid while routing, Best solution is to reduce the grid size.

  • tmd63
    in reply to excellon1

    OK. SO Cadence grid-less routing is non-existent. OK. Got it.

  • Dale Peterson
    in reply to tmd63

    I've worked on a bunch of design tools over the years. The gridless is a term that truly means that graphics are allowed to shift to the smallest grid and accuracy settings that the tool can allow. Some tools have a switch to hit that automatically cranks the grid setting down to the smallest by default. In OrCAD well, there is no "Gridless" switch option.  But, you can still achieve the same results. As an example.-- In a Metric design with an"Accuracy" setting for 2 places in (.01). You would then need to set your design grid to .01 as well to achieve the gridless effect. Try it. 

  • RFinley
    in reply to Dale Peterson

    Just check the placement grid, 0.1mm is reasonable, or you'll look like you mixed english and metric settings.  My team won't let that go..

    Routing grid is really arbitrary if your clearance isn't crazy small.

  • excellon1
    in reply to tmd63

    Hi the term gridless routing really stems from "Auto Routers". In the early 90's there was a big push for autorouters that would do a good job of routing a board and that is where the term came from. Some PCB tools have a option called "Snap to grid" Cadence is not one of them. The cursor in cadence does not snap to a grid "PITA" Imho as the cursor seems to float while routing objects.Even doing things like a move component you will notice that pins on footprints are snapping to the grid but the cursor is just free wheeling. It seems opposite to what pretty much any other pcb tools offer. Doing things like a move copper pour that is off grid or on a sub integer grid is another PITA. You got to do move then bit twiddle right click snap to etc just to get the copper pour to snap to a grid.

    I think you bring up a good point on gridless but before that can be achieved someone at cadence needs to get a handle on how that cursor works.

    As I pointed out earlier your best option while routing is to change the grid size. Changing the grid can be automated and assigned to a hot key so you don't have to make a trip to the toolbar to setup the grid.

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