pcb-rnd knowledge pool

Abstract: How to use the MUCS external autorouter with pcb-rnd.

  Automatic routing of PCBs is an interesting topological problem and various approaches exist for doing it.

Both mainline gEDA PCB and pcb-rnd support simple autorouting of selected rats with the "Connects->Auto-route selected rats" menu option.

The "rats" are simply the flying wires indicating connectivity in the absence of copper trackwork, polygons or pours to complete the connection.

We begin with an example of automatic tracks laid down by the default autorouter in gEDA PCB and pcb-rnd.

We start with a layout showing the components and rats

After running the built in autorouter, we get the following

As can be seen, the autorouting gives a functional result, although arcs and forty-five degree corners are not supported.

Preliminary support for importing of MUCS autorouter designs, allows this additional router to now be used more easily with pcb-rnd.

The File menu in pcb-rnd allows a unixplot file to be loaded. Unixplot (.pl) files are the files that the MUCS autorouter generates that define the tracks and vias making up the routed board

The unixplot files exported by the MUCS autorouter are named either lines.l1, lines.l2,... etc or pads.l1, pads.l2 ... etc, thereby indicating which layers the lines or pads are on

And here are tracks imported from the MUCS autorouter...

The tracks are imported into the currently active layer, which in this case, was the top signal layer.

Here is a screenshot of the corresponding vias imported from the same MUCS test layout:

Having implemented the necessary code to directly import MUCS via and track outputs encoded in unixplot format, the only remaining code still required is an export plugin to replace the pcb2ncap C++ standalone utility formerly used for conversion of .pcb layouts to MUCS format inputs. This is planned for the near future. The pcb2ncap utility predates the current gEDA pcb centimil file format and will not work on current layouts.