gEDA-user: Modular designs (was Re: Multi-page, non-hierarchical schematics?)

[Randall Nortman <geda-lists@xxxxxxxxxxxxxxx>]

On Fri, Jul 13, 2007 at 06:36:25PM +0100, Peter TB Brett wrote:
> On Friday 13 July 2007 18:26:09 Randall Nortman wrote:
> 
> > But assuming I'm not, what is the absolute simplest way to create a
> > flat hierarchy?  
> 
> (1) Create each page as a separate .sch file.
> 
> (2) Use the autonumbering dialog to number your parts, with refdes starting 
> from 100 on the first page, 200 on the second page, 300 on the third page, 
> etc.
> 
> (3) Put *all* the .sch files as arguments to the gnetlist (or gsch2pcb) 
> invocation.

If only I'd planned this all out from the start.  The problem is that
I'm taking an already completed project (schemated and layout),
snipping out part of it and adding more on.  For the part that's
already done, I already have refdeses assigned and matching between
schematic and layout, and I don't know of any convenient, ready-made
way to renumber a .sch and .pcb in parallel (short of writing my own
script to do it, which does not count as "ready-made").

Of course, even though the current refdes assignments are all over the
map, I could still pick some number greater than any currently
assigned and start from there on the new pages.  It just won't be
particularly clean that way -- lots of skipped numbers.  But that's
really only a problem if you're obsessive-compulsive like me. ;)

This has actually gotten me thinking about modular designs in general
-- I find myself wanting to do small runs of semi-customized boards,
each of which is a mix and match of bits of boards that I've already
designed.  It would be nice if this modularity could be captured well
in both gschem and pcb, so that I can mix and match my modules in
gschem and then import that into pcb, which already knows the layout
of each module.  Then for each new semi-custom board I only have to
draw the connections between the modules.  How doable is this right
now or in the near future?  Seems to me that I can copy & paste in
both gschem and pcb, but getting the refdeses to match up would be
very difficult, unless I'm missing something.

Maybe actually a pretty simple script could do it -- design each
module with refdeses starting at 1, then have a script which can just
add an offset to each refdes in both a .sch and .pcb file and write
out the new files, and tell you what the offset should be for the next
file to avoid refdes conflicts.  Then you load all the .sch files into
gschem and set up the connections to get a netlist file, then open up
pcb and load/paste each sub-layout in, then make the inter-module
connections.  This method creates a lot of temporary files, and a lot
of manual bookkeeping, but it would work, right?  Well, except for
slotted parts, which would be difficult to share between modules at
the layout level.

I assume I'm not the only one who has wanted to make mix & match
boards like this -- how have other people handled it?


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