kicad-developers team mailing list archive

[Andy Peters <devel@xxxxxxxxx>]

> On Mar 5, 2018, at 11:49 AM, Russell Oliver <roliver8143@xxxxxxxxx> wrote:
> 
> In terms of automatically arranging  components a force directed graph algorithm may work quite nicely, especially if the algorithm is seeded with the layout of components on the schematic. 
> 
> A simplistic version would be to just arrange components on board sheet as to their position on the schematic sheets.

That approach might be fine for something like a VME CPU board filled with 74xxx TTL parts, but modern designs have too many other considerations. For example, most things fit into some kind of enclosure, and as such the mechanical constraints matter, and then trying to draw a schematic to represent placement can make a mess of things. What if the person drawing the schematic has no idea at the start what kind of enclosure will be used?

The “seeding” can be in some cases inferred from the netlist and connections. This goes to that, that goes to something else, and this that there ends up being in the middle. pcbnew’s netlist import generally keeps parts on the same schematic page together. Start with stuff that needs to be located specifically because of mechanical concerns. It usually turns out that parts will go whether they need to go, and that becomes obvious once you have them all on the canvas and the rats nest is visible. You start with the big parts and fit the supporting parts around them.

I can’t think of any board I’ve done in the last {harumph!} years where I drew the schematic in a way that reflected the final parts placement.

-a