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

[Egil Kvaleberg <egil-at-NOSPAMkvaleberg_dot_no>]

On Fri, 2002-11-22 at 18:44, Major A wrote:

> The one thing I have
> not been able to work out yet is how strongly the schematic editor
> (gschem I suppose) 

gschem is turning out very nicely, I must say, and is very useful as it
is.

> 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.

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.
	
> Is there any need for it
> at all?

I'm afraid so. 

It is always *possible* to manage without, but proper backannotation is
really a good way of avoiding hassle and errors. 

> 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. 

Egil
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