kicad-developers team mailing list archive

[Henner Zeller <h.zeller@xxxxxxx>]

On 5 June 2015 at 11:00, Andy Peters <devel@xxxxxxxxx> wrote:

>
> > On Jun 4, 2015, at 9:26 PM, Chris Pavlina <pavlina.chris@xxxxxxxxx>
> wrote:
> >
> > The assignment of footprints to schematic symbols is largely a KiCad
> > quirk. Many other tools consider a component to be a single package
> > containing symbol and footprint. In my own library I have a part per
> > actual electronic part (one called MMBT3904, for instance), which
> > already has the Footprint field set from the very beginning, no mucking
> > about with the nightmare that is cvpcb.
> >
> > Also, footprints are much more critical, in that you have to get all the
> > dimensions very correct, so it makes much more sense in terms of being
> > less error-prone to have multiple symbols linked to one footprint than
> > one symbol linked to multiple footprints.
>
> At risk of reiterating myself again, what Chris describes above is how
> professional engineering groups do their libraries. Every company I’ve
> worked for has a vetted parts list and the PCB layout library includes only
> those parts. The symbols and footprints are married to a part number. Under
> no circumstance would someone choose, say, an NPN transistor from a library
> and then later match it to a footprint and to something that can be
> ordered. The chance of an expensive fuck-up happening is way too high.
>

Agreed. The way this internally should be represented is something like
   IRFZ44N = (generic PowerMosfet with logic names) + (G=1 D=2 S=3 pin
assignment) + TO220 with pin 1,2,3.

That way, it minimizes the repetition of the symbol definition, but then
ties the important information that makes a particular product the way it
is together.