Re: gEDA: design decisions: PCB<->schematic

[Magnus Danielson <cfmd-at-NOSPAMswipnet_dot_se>]

From: Andrew Dyer <adyer@enteract.com>
Subject: Re: gEDA: design decisions: PCB<->schematic
Date: Fri, 22 Nov 2002 12:18:14 -0600

> > Now the question: has anyone ever successfully made use of two-way
> > communication between the layout editor and the schematic editor? Does
> > it really make sense to make changes to the schematic diagram when
> > someone rearranges connections on the PCB?
> 
> I prefer to have them mostly separate with a well-defined /text based/
> interface between them.
> 
> > I'm the last person to know the answer, having built all my projects
> > so far on the PCB directly without any schematic diagram.
> 
> There is definitely a need for back annotation - the simplest example
> is renumbering the reference designators on the board.  Another
> example is using something like a 4 resistor SMT pack for termination
> on a bus, where in layout you want to swap which resistors in a pack
> go where to make the layout compact/simple.  Forwarding that back into
> a schematic can be painful and error prone on something like a 256-bit
> memory bus.

While this is true, the forward-backward annotation between schematic and PCB
layout tools where invented to help avoid the troubles that creep up with all
those annotations. A good friend of mine who works everyday with electronics
and CAD tools says this is one of the feature he likes most with his current
tool. He basically says "If you're ever to write such a tool, you *really* want
to have both the schematic and PCB in the same database!". Same database or
not as a technicality is one thing, avoiding the sync problem between them is
however a real concern for at least some people.

So, in a generalized way, eventually will some means of keeping schematics and
PCB layout in sync be necessary to implement. The technical details on how this
is solved is left for implementors to decide.

That I also want to see a natural connection to things like CVS for both
schematics and PCB is another thing.

Cheers,
Magnus