Re: gEDA-user: Schottky symbol polarity

[Dan McMahill <dan@xxxxxxxxxxxx>]

Randall Nortman wrote:
> This was mentioned by somebody else on the list last year, but the
> discussion turned to problems with simulating SMPS's on ngspice, and
> the original issue was never really addressed:
> http://archives.seul.org/geda/user/Oct-2006/msg00167.html
> 
> The issue is that schottky-1.sym has the cathode on pin 1 while all
> the other diodes (that I've checked) have pin 2 as the cathode.  Is
> this just an old mistake that can't be fixed now because we have to
> preserve backward-compatibility?  Or is there some logic to this?  Is
> there any way to add a visible warning to the symbol (as an attribute,
> presumably, or permanent text) without breaking backward compatibility,
> and then create schottky-2.sym with the correct polarity?
> 
> I ask because I just ran into it (again) myself, and it was only a
> little voice inside my head saying "Wait, wasn't there some problem
> with this symbol that you ran into last time?" that kept me from doing
> it wrong again.  Granted, it only makes the silkscreen wrong, so once
> you figure out you've made the mistake you can just mount the part the
> other way.  But still, that's a mistake that could fry some components
> if you don't catch it in time.


This is a clear case of why you need the concept of a component that 
provides the mapping from symbol pins to footprint pins and also from 
symbol pins to netlist pins for various simulators.  Its really the same 
problem.

It is why I generally believe in using a script to generate heavy 
symbols for each component but currently geda doesn't quite support the 
idea of letting a component have more control over how it netlists for 
spice.

As soon as you change the existing symbol someone will get burned when 
it no longer maps correctly to whatever footprint they happen to be 
using for a schottky diode.

-Dan






_______________________________________________
geda-user mailing list
geda-user@xxxxxxxxxxxxxx
http://www.seul.org/cgi-bin/mailman/listinfo/geda-user