Re: gEDA-user: Symbols and footprints and stuff, oh my
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 geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Symbols and footprints and stuff, oh my
Martin Maney wrote: > So I did a smallish circuit full of discrete transistors and Rs and Cs, > and found usable footprints for all of them, but the pins from the > transistor symbols - npn-2 and pnp-2 - didn't match the numeric pin > names on the footprints. Most gschem and pcb users make a library of their own symbols with the details of parts they use -- a heavy symbol library. The distribution library is not very complete, and gedasymbols.org is where some have put up their symbols and pcb footprints to help choose a library of what you need. I came across Bill Wilson's discussion of > transistor pinouts: > > http://furrr.two14.net/cgi-bin/dwww/usr/share/doc/geda-doc/wiki/geda_transistor_guide.html > > At first I didn't care for it, having used other tools with a more > heavyweight symbol approach, but I've decided he's on to something. > I'll talk about a half-formed thought about a possibly better > compromise between lightweight and heavyweight symbols, but for the > moment I'm just wondering if (1) Bill's approach is generally approved > of, Sure, it's what's feasible for the distribution made by volunteer action. But then, it's not what the experienced users stay with... You will want to develop a library to suit your own aims. John Griessen -- Ecosensory Austin TX ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Symbols and footprints and stuff, oh my
Martin Maney wrote: So I've been fairly happy with these tools (currently using the > packaged stuff from Ubuntu's Gutsy release), but there are a couple > little things I've run into, aside from the peculiar behavior that > arises when one tries to make an oval pin and use it in a ground > plane... > > So I did a smallish circuit full of discrete transistors and Rs and Cs, > and found usable footprints for all of them, but the pins from the > transistor symbols - npn-2 and pnp-2 - didn't match the numeric pin > names on the footprints. This is a known problem in the current flow. I think the right answer here 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. > gsch2pcb spit out a script that I would have > thought was intended to deal with that sort of thing, but no, it's all > just identities like this: > > ChangePinName(Q9, E, E) > ChangePinName(Q9, C, C) > ChangePinName(Q9, B, B) 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. > I thought I did everything as described in the schematic-to-pcb > writeup, but if this makes you think I forgot a step don't hesitate to > mention it, of course. > > 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 > variant; then too, I don't really want that square pad, useful as it > was for identifying the numbering the footprint used). While chasing Does it match the JEDEC drawing? > links all over creation, I came across Bill Wilson's discussion of > transistor pinouts: > > http://furrr.two14.net/cgi-bin/dwww/usr/share/doc/geda-doc/wiki/geda_transistor_guide.html > > At first I didn't care for it, having used other tools with a more > heavyweight symbol approach, but I've decided he's on to something. > I'll talk about a half-formed thought about a possibly better > compromise between lightweight and heavyweight symbols, but for the > moment I'm just wondering if (1) Bill's approach is generally approved > of, and (2) if anyone's already run up footprints (I guess the existing > symbols will suffice, aside from that letters vs numbers thing) for > this approach. I personally thing a heavyweight symbol library is the only way to go. 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 :( -Dan ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
