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Re: gEDA-user: Parts!



DJ Delorie wrote:
> Way back when, when I use cadstar, what they did was have multiple
> alternatives within each symbol and footprint.  So, the mapping was
> generic part -> generic symbol -> alternative, and generic part ->
> specific part -> footprint. ...


That is what most CAD systems do. Usually you can't select farther down 
than footprint, like "oh, I want one with the solder mask tucked some 
more". That would require making a new footprint with a new name to it. 
Then in programs like Eagle this new footprint must also be assigned to 
a part or it won't show up in the footprint selector for that part.


>                   ... This thread makes me think we need to
> allow for footprint alternatives in pcb, so it would be:
> 
> generic symbol -> alternatives (positive vs negative logic, orientation, design, etc)
> 
> generic symbol -> generic part
> 
> generic part -> specific parts (manufacturer?)
> 	(note: this does symbolic pins -> numbered pins too)
> 
> specific part -> slotting(grouping) -> gschem (this is done in gschem)
> specific part -> footprint class -> specific footprint
> 
> specific part -> vendor, costs, inventory, etc.
> 

This would be leather seats plus champagne cooler :-)


> footprint class (or specific) -> slotting(numbering) -> gschem (this is done in pcb)
> 

That part would IMHO only make sense if or after the broken annotation 
and power pin issue gets resolved.


> For SOP footprints, for example, we could "outline around pads" and
> "outline between pads" options, or project-specific alternatives like
> "extra clearance".
> 

Nice, but it doesn't have to go that far. Most people are used to making 
  special footprints. Like one for Rogers, one for FR4 and maybe one for 
<gasp> the super-saver phenolic projects, then keep using them all the 
time. When I ask my layouter to make a change because of high voltage or 
something he just creates a whole new footprint and calls it joerg_d2pak 
or whatever. It doesn't consume much of his time because he cuts and 
pastes from the standard one.

-- 
Regards, Joerg

http://www.analogconsultants.com/



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