Re: gEDA-user: symbol files

[Bill Gatliff <bgat@xxxxxxxxxxxxxxx>]

Peter TB Brett wrote:
> On Thursday 12 November 2009 19:56:25 Kelvin Gardiner wrote:
>   
>> Having a quick look at a symbol file it seems there is no way to define
>> different pin positions and order for different packages. Which is what
>> Peter implied in his reply.
>>     
>
> Correct.
>  
>   
>> Is there any plans to work on this feature?
>>
>>     
>
> Not that I am aware of.  Feel free to submit patches though!
>   

This is a potentially tricky feature, because for example some of the
microcontrollers I have worked with have pins that aren't available on
certain packages.  There are also cases where the pin mapping is just...
wierd.  Consider even the lowly Atmel ATtiny45, which comes in DIP8 and
MLF20.  Yep, an 8-pin package and a 20-pin package.  Guess which one has
a bunch of no-connects?  :)

IOW, I think that in the general case it isn't possible to pick a symbol
independent of its package.  True, it works for a lot of devices, but
not all of them...

Maybe a better way to approach this problem would be to provide for a
meta-comment field or attribute in the symbol file that could be used to
refer the user to alternative symbols for the part.  That would let you
have one .sym file per component-footprint, but also provide for a GUI
feature to guide the user to the list of available options.  Hopefully,
older versions of gaf would just ignore that attribute.

For symbols that worked properly for all available footprints for the
part (DIP8 vs. SOIC8, for example), maybe another attribute would
trigger the GUI to let the user pick between those footprint names.


Just a thought.


b.g.

-- 
Bill Gatliff
bgat@xxxxxxxxxxxxxxx



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