Re: gEDA-user: RFC: Towards a better symbol/package pin-mapping strategy

[John Doty <jpd@xxxxxxxxx>]

On Jun 28, 2009, at 3:23 PM, Bill Gatliff wrote:

> Stefan Salewski wrote:
>>
>> Currently we (may) have different symbol files for the the same  
>> device
>> with different footprints. So we have the same graphics elements
>> multiple times. This is redundancy, wast of storage area, and it  
>> makes
>> it more work to modify the graphics. So it is not a perfect solution.
>>
>> And replacing a symbol in a schematic only because we want a  
>> different
>> footprint is not a very natural way for me.
>>
>
> Right.
>
> To me, the symbols in a schematic are strictly that--- symbols.  Why
> should I switch to a visually-identical symbol, just because the pin
> assignments underneath have changed?

Why are you hung up on the form the container of the information  
takes? If the symbol file contains the same graphics, isn't that the  
same symbol from a graphical point of view? Why do you consider it  
different?

>
> Maybe we're philosophically disagreeing on what a schematic diagram
> represents.  I don't think of them as wiring diagrams, but as signal
> flow diagrams.

They represent topology. That's the *substance* (you cannot deduce  
signal flow from a schematic without extra knowledge: that's part of  
the reason DRC doesn't work very well). Now, use the native  
capabilities of gEDA and your OS to create that substance, rather  
than fighting them.

>   PCB's job is to turn that into a wiring diagram.  Or
> something like that.
>
> Apparently to some, schematics are also wiring diagrams.

To me, they're topology. The same schematic imported into projects  
with different symbol files thus may wind up representing different  
wiring. That's part of the power of the project symbol approach.

A directory full of symbols is a pretty decent database.

>   Cool.  So put
> wiring information into your symbols.  All of them.
>
>
>
> b.g.
>
> -- 
> Bill Gatliff
> bgat@xxxxxxxxxxxxxxx
>
>
>
>
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John Doty              Noqsi Aerospace, Ltd.
http://www.noqsi.com/
jpd@xxxxxxxxx




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