Re: gEDA-user: pin swapping idea

[John Doty <jpd@xxxxxxxxx>]

On May 8, 2010, at 10:43 AM, kai-martin knaak wrote:

> DJ Delorie wrote:
> 
>> 
>> Had an idea about back-annotating pin swaps.
> 
> Why is this on the devel list, where mere users are not allowed to write and 
> hardly read?
> 
> 
>> The big "issue" is figuring out how to back-annotate from pcb to
>> gschem.  So... why do we need to? 
> 
> Because a schematic should contain the information on which slot a symbol 
> corresponds to. 
> 
> 
>> gschem need not know about physical packages or pins, ever, unless you
>> want to back-annotate a whole board (or merge the pinmap into a
>> separate set of schematics for reference). 
> 
> gschem may not need to know, but I need to, when I look at the schematic.
> 
> A pretty common scenario with my kind of analog prtojects: For some reason I 
> know, there is a problem with  a certain analog switch. This switch happens 
> to be one of the four slots of IC7. The value of the slot attribute is 
> visible on the schematic and says it is number 1. Thus I know, I have to 
> poke at pin 1-3 of IC7 for debugging.
> If the slotting information would reside in the layout only, I'd have to 
> back-engineer form the actual tracks on the layout which pins to look at.
> 
> 
>> How confused would gschem get if we omitted pin numbers from it
>> completely?

gschem doesn't get confused, but gnetlist does.

> 
> Me, the reader of the schematic would be quite confused. I deliberately have 
> pin numbers printed on the schematic for more complex ICs. This helps a lot 
> during debugging stage of prototypes. It provides a convenient way to know 
> at what pin to stick the scope probe.

For a clean flow, I'd want the annotated schematics that go into the documentation to be distinct from the source schematics that I edit. I emphatically reject "back-annotation" as a serious problem for reuse and automated flow. Others have other ideas, so any facility should support both flavors of annotation. Of course, a well factored facility would make this trivial. But, for example, wiring it into gschem would problematic.


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




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