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Date: Sat, 24 Oct 2015 01:10:57 -0400
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From: DJ Delorie <dj AT delorie DOT com>
To: geda-user AT delorie DOT com
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Subject: Re: [geda-user] Pin mapping (separate symbols from mappings)
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Reply-To: geda-user AT delorie DOT com


> IIRC at the moment it give NO WARNING for duplicate refdes, which is just
> inexcusable.  To be fair you can blame this on pcb but still...

It's common to break large chips (like MCUs) into separate symbols to
manage them better, which means that a duplicate refdes is allowed (in
fact, required) in those cases.

What should not be allowed is duplicate pins, module how slotting is
implemented.  The problem I forsee is that "duplicate pins" is a
problem that will be solved in the netlister *if* slotting is moved
out of gschem, resulting in duplicates being allowed in gschem,
resulting in ambiguity.

So there's three cases:

1. One symbol to one component, refdes should be unique, no problem.

2. Many symbols to one component (MCU), refdes must be same but pins
   should be unique.

3. Many symbols to one component (SLOTTING), refdes and pins may be be
   same or unique depending on how slotting is implemented.

> Schematic pages except for subcircs are obsolete IMO,

I use separate pages because I often implement subcircuits separately
for testing.  For example, I might fab just the power supply.  In my
powermeter board, 15 of the 16 channel circuits were implemented with
a script that copied the first channel's page.

> If you need to print your schematics it's because your CAD sucks
> somehow.

Or because you want to debug and the bench doesn't have its own
monitor.  Or because you're writing an article and need the schematic
split into describable chunks.  Or you're writing a manual and the
schematic needs to fit onto a printable page.  Or you're breadboarding
it and you're marking off pins as you connect them.  Or you're doing a
science fair project and you need posters :-)