Re: gEDA-user: PCB format wishlist

[Andrew Poelstra <asp11@xxxxxx>]

On Mon, Sep 06, 2010 at 04:49:32PM -0400, DJ Delorie wrote:
> 
> > Why have any distinction between "footprint" and other fragments of
> > layout (like hierarchical blocks)?
> 
> Because PCB needs to deal with boards at the semantic level, not just
> the physical level.  Padstacks have to "exist" at the element level so
> they can be tied to the netlist, for example.  A padstack elsewhere
> has to be managed differently.
>

We can store mappings in the file, though.

Suppose I've got a footprint containing one element, U?, with 4 pads,
P1 P2 P3 and P4. If I then bring the footprint into a pcb layout, the
file would look like:

element: U5
  mapping:
    # Refdes map
    U?: U5
    # Pad map
    P1: U5-P1
    P2: U5-P2
    P3: U5-P3
    P4: U5-P4
    # Layer map
    silk: silk
    component: layer1
  data:
    # Actual data, or import directive, or whatever

In actuality, if we had element groups, and allowed pins to be addressed
through their group (U5-P1, U5-P2, etc), there would be no need to map
the pads explicitly.

I think that "pad" should be a primitive type, which is just a textual
identifier. It could then be attached to geometric shapes, be a member
of a group, and be referenced in netlists.


Andrew
 


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