Re: gEDA-user: A couple o' questions

[John Doty <jpd@xxxxxxxxxxxxx>]

On Apr 7, 2006, at 5:43 PM, John Sheahan wrote:

> Mark Rages wrote:
>
> > The pintype *is* obvious for the "fistful of TTL chips" approach to
> > digital design, which was commonplace when EDA systems were first
> > getting developed.  Maybe the pintype DRC is a bit of an anachronism.
>
> maybe DRC applies much better to some types of designs  than others.

Yes!

> Which would imply to me that DRC should be used judiciously.

Yes! That's the problem with gnetlist's drc2 hard sell.

> Perhaps the components themselves should know whether that are good  
> at being DRC'd.    Or a DRC rule decks be chosen for purpose?

I think that having pintype default to "pas" would be constructive.  
That should essentially turn off the pintype DRC for a component  
whose author couldn't figure it out.

> I never figured out the DRC attributes for a bipolar tansistor at  
> board level for exmaple.  john

Yep. The roles of the pins aren't properties of the device: they're  
determined by how the device is used. The emitter might be  
'in' (common base), 'out' (common collector), or 'pwr' (common  
emitter). So, use the escape hatch and call it 'pas'. Won't get  
checked, but won't cause an error. Yeah, I know, that's not obvious  
unless you understand the details of how DRC works (or doesn't).  
That's why 'pas' should be the default.

John Doty              Noqsi Aerospace, Ltd.
jpd@xxxxxxxxxxxxx