I'm running into an issue with symbols and gschem.
I think gEDA and friends are a good idea, and I'm going to attempt to
make the switch from closed-source packages. However, one big glaring
issue I've noticed in gEDA is the state of the symbol library. The
organization is pretty bad. Also, according to the tutorials I've read
for capturing a schematic and then laying it out as a PCB, you have to
hand edit attributes like 'footprint' in several of the symbols after
dropping them into the schematic. This obviously isn't the best way to
have things set up; it would be better if these symbols were already
loaded with the useful information, even if that means a larger library
to choose from.
In addition, in Electronics Workbench (the closed package I'm most
familiar with), I really liked the idea of having resistor and capacitor
symbols available with the resistance or capacitance values already set
to standard commercially available values. I know this is just a
preference, but I thought it was convenient and worth the increase in
symbol library size. Rather than drop in a generic resistor and then
edit its attributes, you can just pick the resistor from the symbol
library with the required value and move on without editing anything.
Anyway, I figured I would just build my own custom symbol library to my
own spec, since all I use are basic passive parts, a few transistors and
some diodes. It shouldn't be too hard to just build symbols as I need
them. I read through the guide at
http://www.geda.seul.org/docs/current/fileformats/index.html detailing
how to build a symbol, and starting building a 2N5551 transistor model.
Now the problem I have is in the visibility of attributes. I intend to
have all the useful attributes filled in (stuff like documentation and
footprint), but these aren't values that need to be visible on the
schematic once the device is inserted into the schematic. The problem
is, a section of the .sym file like:
T 1400 0 8 10 0 1 0 0 1
footprint=TO92
gets ignored by gschem when the symbol is inserted. Checking the
attributes of the symbol only shows attributes from the .sym file that
were marked as visible. The sixth field being set to '0' is supposed to
make the following attribute invisible, but instead, gschem just
considers it something to be thrown away. Saving the file that the
symbol was imported into and checking it with a text editor confirms
that anything that wasn't marked 'visible' is stripped off a symbol.
There're lots of attributes that need to be kept associated with the
symbol in the file, but not necessarily displayed on the schematic.
Would it be possible to modify gschem so that attributes in the .sym
file that are marked as invisible still get stored in the .sch file, but
just stay marked invisible so as not to appear on the schematic?
On the previous note: I don't know what the protocol is for building new
symbol sets, but once I'm done with the resistor and capacitor sets in
standard values, I'd be happy to tar them up and submit them. Would
there be any interest in them?
Anyway, thanks for all the fine work, and thanks in advance for any
advice I can get here.
- Jonathan Hanson
Louisiana State University
Department of Physics and Astronomy
