On Tue, Dec 04, 2007 at 06:49:10PM -0500, Dan McMahill wrote: > This is a known problem in the current flow. I think the right answer here
As you'll see, I don't disagree, basically, about the long-term answer. Are there any shorter-term solutions planned, or is that the realm of a little sed script or some such that each of us arranges as we prefer? > is to use a script to generate a library of heavy symbols for things like > transistors. Search for a post by me that has something like symbol > generator in the body. My thinking, as far as it's gotten, goes something like this: 1) it would be really nice to be able to maintain close compatibility with the lightweight symbol approach. One thing I don't like about really heavy symbols (at least in the form I've encountered them in other software) is that they're a pain to change (this is likely more of an issue for schematic -> simulation). In principle there could be a convenient "change [transistor] type", but it always seems to bite me with a half-assed "let the user delete it and put a new one in by hand", with messye details like part numbering and such left to fall where they may. So my thoughts are along the lines of what would be the least that would allow the glue tools (schematic -> netlist, -> minimal pcb, etc.) to do the work? For transistors, the convention seems to be to use, eg., value=2N3904. Now, suppose there were a package=TO92 attribute, and a simple table of value+package -> footprint+pin_mapping... with the option to override the footprint at least with an explicit one for backwards compatability (or a package not in the table)... Something similar (perahps the same table?) would take care of simulation, though for most parts I'm familiar with the package wouldn't change much except the thermal resistance. But I don't play around in the GHz range, so I dunno if it should be one table or two. Anywhow, this doesn't *require* any changes to gscheme (or PCB or *spice), though there's certainly room to make it more conveninent to select parts there. But if I were going to try for a proof of concept - which I really haven't time for right now, gotta *use* the programs to get some boards prototyped in the next couple weeks - it could be done by hand and wouldn't be much different than current usage that way. > On some other symbols, you might see things like the pin called "1" being > renamed to "IN" or "OUT". That file is purely for cosmetic purposes, i.e. > if you skip it, your final artwork will not change. Ahhh. It did do something with + and - for polarized caps, didn't notice if it was actually necessary. >> Then there's the footprints, which are good enough to use but not >> ideal (eg, the m4 TO92 calls out pin 1 backwards from what seems to be >> the usual practice for that package, at least for the inline-pins > Does it match the JEDEC drawing? I thought I'd come across a scan-in-pdf of the TO92 docs, but I can't find it now; perhaps that's at the lab. I do have the closely-related TO226, and JEDEC doesn't show pin numbers on that. It refers to "pin two" w.r.t. the triangular pinout (leadformed from inline or molded that way), but of course that's the same either way. :-( > I hacked together a proof of concept thing for transistors and it works > well. I posted it to the list a while back. I'd send again, but I'm in > the middle of trying to find a computer to read that hard drive :( Bah, more stuff I need to look for. :-) -- Happy Holidays! Cry "Charge it!" and let slip the dogs of more. _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
