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

[Magnus Danielson <cfmd-at-NOSPAMswipnet_dot_se>]

From: Egil Kvaleberg <egil@kvaleberg.no>
Subject: Re: gEDA: design decisions: PCB<->schematic
Date: 22 Nov 2002 20:10:24 +0100

> > and the PCB editor should be tied together. In many
> > commercial packages they are basically part of one big program --
> > Eagle has this "forward-backward annotation", for example.
> 
> Hate the "one big program" idea.
> 
> A netlist concept and design rule check is crucial for any layout
> program. At least for mere mortals, that err from time to time.

Hear, hear!

> Now the question: has anyone ever successfully made use of two-way
> > communication between the layout editor and the schematic editor? 
> 
> One thought: Instead of going via a netlist, would it be an idea to
> extract netlist and component information directly via libgeda, the
> interface library that gschem uses? I'm not sure quite how it would work
> out, but at least the reverse annotation problem would be made much
> easier in that one could modify the schematic just as gschem would.

I've thought about this too. You could even be able to create an internal
representation which forms an internal virtual view on things, as if they where
the same database, where they infact are in separate files. I don't think it
needs to be done in a fancy way to actually work. Nothing that can't be done
with 600 classes and hierarchial inheritence of at least 30 in depth.

> > I'm the last person to know the answer, having built all my projects
> > so far on the PCB directly without any schematic diagram.
> 
> Which sort of reminds me of an old idea of mine: Whereas a schematic
> drawing is super for visualizing analog circuits and also some digital
> circuits (gate logic, for instance), it is in fact pretty unsuited for
> drawing various types of processor systems, for instance. In this case,
> a textual specification would be better, listing the components, and 
> then describing the signals and which components they connect. 

Another way to view it, I often find myself reverse engineering old stuff
where even the propper documents doesn't give of near as much knowledge that is
needed these days. Having reverse-engineered a 100 TTL chip board from two
scanned images and a PDF of scanned hand-written schematics I know what I would
value, BTW, gschem where used with great succsess there, only a few anoying
details.

While reverse-engineering is not the normal type of task, when it needs to be
done, it would not hurt if there where a good suite of tools that could handle
it... too.

Cheers,
Magnus