gEDA-dev: Thoughts on buses in gschem

[John Luciani]

On 7/12/06, Dan McMahill <dan at mcmahill.net> wrote:
> Steve Meier wrote:
> > Peter,
> >
> > I am very interested in hierarchical bus structures. A lot of what I am
> > going to say is probably obvious.
> >
> > Buses should be capable of grouping a large number of nets together.
> > Busrippers are used to join nets to buses. The question is which
> > position within a bus the joined net connects to?
> >
> > I agree there needs to be some method for organizing the nets within a
> > bus and then for the busripper to selectively attach to one of the bus
> > contained nets.
>
> I guess I'm not a big fan of needing to have a special busripper or a
> special 'bus wire'.  I think they're both somewhat redundant although I
> can perhaps be convinced otherwise.
>
> The way cadence handles it is all wires are basically equal and if
> they're fat (like for a bus) or thin (like for a wire), its strictly for
> appearance.  They way a wire becomes a bus is by labeling it or by
> connecting to a pin which is a bus by virtue of it carrying more than 1
> signal.
>
> bus ripping is done simply by connecting up a wire to the bus and
> putting the right name on it.

My preference would be for the Orcad method (which sounds similar to the Cadence
method).

As I remember the Orcad method you run a net from the pin and name the net.
You place a bus entry symbol to graphical connect the net to a bus.
The connection is done by net names not the bus. Labels on the bus do not
affect connections.

What would be nice is a command to label a group of selected nets.
For example:
  (label-nets "A0" "A15")  would label selected nets from top to
bottom (or left to right)
  with net names "A0" .. "A15".

(* jcl *)

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