kicad-developers team mailing list archive

[Wayne Stambaugh <stambaughw@xxxxxxxxx>]

On 6/5/2015 2:00 PM, Andy Peters 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.
> 
> Pardon my Jersey.
> 
> -a

There is absolutely nothing preventing you from doing this.  The reason
this isn't done is the list of transistor, op-amp, regulator, etc.
symbols would be huge and a maintenance nightmare given our resource
limitations.  The current symbol libraries are a good compromise.  There
are really only a few variations for most 3 pin devices such as
transistors and diode pairs.  Trying to provide a fully defined symbol
for every transistor would be a huge under taking.  Our solution may not
be ideal but I'm not sure I want to sift through thousands (tens of
thousands?) of transistor part numbers to find what I'm looking for.  I
wonder how well Henner's component chooser search code would handle that
number of symbols.  That would probably take longer than just making
sure my transistor symbol and footprint pin out are correct.  However,
I'm betting if you would offer to do this, the library maintainers would
not object.

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