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

[Jim Battle <frustum-at-NOSPAMpacbell_dot_net>]

At 05:44 PM 11/22/02 +0000, Andras wrote:

>Hi,
>
>I have thought out some of the details of the upcoming rewrite of
>Lasagne, and this time, I am going to try not just to make a good tool
>for myself, but a really good PCB design program. The one thing I have
>not been able to work out yet is how strongly the schematic editor
>(gschem I suppose) 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.
>
>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?
>
>Doing one-way communication is rather easy to implement, I think I
>have a good plan for that, but I'm quite sure the other way
>(PCB->schematic) would be very hard to add. Is there any need for it
>at all?
>
>I'm the last person to know the answer, having built all my projects
>so far on the PCB directly without any schematic diagram.
>
>   Andras

I think there is no need to get too fancy.  Probably the most 
straight-forward way is the best.  Two-way "hot" linking might make for a 
whizzy demo, but I'd think there is less need for open source software to 
have to invest a lot in "tricks" like this to get customers.

There is definitely a need to feed back to the schematic changes to part 
disignators (some boards use a "geographic" part naming convention), and 
for sure there is need for pin swap.  Ideally for pin swap, the layout tool 
has access to the same pin group information that the schematic has so only 
legal pin swap (and section swap) possibilities are allowed.

Anyway, a simple text file could be generated by the layout program that 
the schematic program could read to make those same swaps & renamings in 
the source schematic.

-----
Jim Battle == frustum@pacbell.net