Re: gEDA-dev: Broken slotting

[John Doty <jpd-at-NOSPAMwispertel_dot_net>]

On Sep 11, 2007, at 8:07 AM, Peter Clifton wrote:

> I should be able to write a fix over the next day or so.
>
> Thanks for confirming the desired behaviour. I was (and still am) a
> little concerned about not having any "contractual" guarantee that  
> every
> symbol will have pinseq attributes start at "1" and end at the  
> number of
> pins on the device. Perhaps this is implied though, by the nature  
> of the
> slotdef attribute.

Can we think this out a little better? Pinseq is a confusing  
attribute, made more confusing by its overloading:

1. It identifies pins for slotdef.

2. It identifies pins for SPICE.

This new recycling approach for SPICE makes it even more confusing. I  
think a spice-slotdef attribute would be better (and backward  
compatible). Maybe also a spice-pinnumber attribute for clarity in  
non-slotted symbols. Then pinseq just becomes the internal pin  
identifier. That would be cleaner and clearer, I think.

But even that's tricky. Consider a quad opamp. Published SPICE models  
for such things generally are for one slot. So, unlike board layout,  
the SPICE netlister should really consider such a thing to be four  
separate components. But this is probably not universal.

I avoid this mess by using non-slotted components in simulations,  
substituting slotted ones for the board design. This bug originates  
from the desire to get the tool to automatically handle the  
difference. But there are so many differences in practice between a  
simulation drawing and a board drawing that that's a very difficult  
road to travel. Perhaps we shouldn't try...

John Doty              Noqsi Aerospace, Ltd.
http://www.noqsi.com/
jpd@noqsi.com




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