Re: gEDA-user: get-package-attribute sometimes returns "?" - ID: 3114991

[John Doty <jpd@xxxxxxxxx>]

On Dec 19, 2010, at 6:38 AM, kai-martin knaak wrote:

> John Doty wrote:
> 
>> Repeat after me: "the library symbols are only starting points".
> 
> Which is a pity and a major weakness of geda/pcb.

Have you used other tools? It's unavoidable for anything that can tackle a broad range of projects. gEDA isn't just for hobbyists, you know.

> 
> 
>> Everybody has their own working style: the library cannot
>> possibly cover everybody's.
> 
> True. However it does not preclude the existence of a library
> that reasonably matches the needs of a large group of users.
> The other EDA packages I had the chance to work with, did a 
> much better job at the library front. You could get quite far
> with their default library. My eagle oriented colleagues hardly 
> dive into the symbol and/or footprint creation business.

And they can't go all the places gEDA can go.

There is nothing whatever preventing somebody from constructing a symbol library that matches *their* notion of a reasonable gEDA flow. Publish on gedasymbols. But I predict that such a person would get numerous complaints from users. All of the symbol complaints seem to come from people who want gEDA to follow a narrow path that is *obviously* to them the path that suits most users, but in fact would only suit a modest subset.

I personally use gEDA for about six kinds of incompatible flow (overlapping categories, take with much salt).

1. Breadboard

Stock symbols, nothing fancy.

2. Small scale printed circuit.

Stock symbols, attach footprint names the layout person will recognize.

3. Large scale printed circuit.

Largely project-specific heavy symbols. Footprints in symbols, not usually promoted or attached. Try to get layout contractor to tell me what footprint names they want.

4. SPICE simulation of circuits for printed circuit realization

Stock symbols, attach the extra attributes. It is presently impractical to simulate schematics as drawn for printed circuit layout. If we could move the semantic processing out of the gnetlist front end, it would be possible to write a SPICE netlister that would work without requiring you to redraw such things.

5. Capture of circuit topology for symbolic analysis (-g mathematica).

These are necessarily small circuits, so I mostly use stock symbols.

6. VLSI design

Only a few of the stock symbols are useful here. I've published (on gedasymbols) a collection of symbols matching the OpenIP VLSI library. One nice thing though, is that at least for the layout flow my customer uses there is no conflict between the semantics of layout and the semantics of simulation, so the netlists I send for layout are verifiable in simulation.

> 
> 
>> Hierarchy->Down Symbol
>> Delete the offending attribute.
>> File->Save As
>> Hierarchy->Up
>> Delete old symbol, add new in its place.
>> 
>> Is that really so hard?
> 
> A GUI oriented work-flow recommended by John D. (!)

Well, in truth, I'm more likely to:

locate whatever.sym
cp the-selected-version-of-whathever.sym ProjectSymbols/whatnow.sym
gschem ProjectSymbols/whatnow.sym
Fix the symbol
fs

Before ever placing it. Often there's already a suitable version in some other project, no fix needed.

John Doty              Noqsi Aerospace, Ltd.
http://www.noqsi.com/
jpd@xxxxxxxxx




_______________________________________________
geda-user mailing list
geda-user@xxxxxxxxxxxxxx
http://www.seul.org/cgi-bin/mailman/listinfo/geda-user