On Sunday 23 September 2007 15:40:42 Dan McMahill wrote: > Peter Clifton wrote: > > On Sat, 2007-09-22 at 20:35 +0200, Stefan Salewski wrote: > >> I think that opamp-1.sym will not be compatible with SOT23-5 footprints > >> -- in TI datasheet of OPA656 pin 1 is output for SOT23 package. Maybe > >> opamp-1.sym is compatible with SC70-5 configuration, which I have newer > >> seen. > >> > >> Or opamp-1.sym and opamp-2.sym are only abstract representations of an > >> OpAmp, without any relationship to a concrete footprint? > >> > >> In any case, there seems to be no symbol in gEDA related to an ordinary > >> OpAmp in DIP8 (or SO8) package. > >> > >> This may look very strange for new gEDA/pcb users. > > > > There are various "heavy" symbols, such as lm741-1.sym. > > > > It is a well known problem though, the mapping between a light symbol > > and a real package is not something which is easily solved. > > which is why I'm in favor of a heavy symbol generator for op-amps like > the one I demonstrated for bipolar transistors. You use a small set of > symbols and then have a text file which is essentially a spread sheet > that for each actual part number (the full vendor part number including > package code) you give the mapping from symbol pin to the footprint pin > # as well as list the actual footprint. Its pretty simple, you don't > have to continually wonder if you have the right footprint or right > pinout, and you only have to maintain a small number of graphical > symbols. Adding new part number is then a snap. You could write a script which does this and exposes the results as a library in gschem. You wouldn't need to actually generate the on-disc files then; you could create the library on-demand from symbol + spreadsheet. (What you're suggesting is exactly what I had in mind when I did the rework of the libgeda library mechanism). Peter
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