Re: gEDA-user: Not mounted parts

[John Doty <jpd@xxxxxxxxx>]

On Jan 25, 2009, at 12:24 PM, Tamas Szabo wrote:

> Hi All,
>
> I need to design a circuit where in some cases a pull-up resistor in
> other cases a pull-down one is necessary.
>
> I have two questions:
> - can I specify attribute 'not mounted'?
> - can I see those parts in the BOM file?
>
> I'm pretty sure, lots of you faced the same situation. Is there a
> convention for this?

No, but there are lots of ways to do this. In some designs, I have a  
gain adjustment resistor. In most cases it should be left out, so it  
has "value=omit". Something like "value=330, not mounted" is  
perfectly legal from the gschem/gnetlist perspective. What happens  
down the road depends on your back end(s).

You are perfectly free to make up your own attributes. I have things  
like "spec=25WVDC, X7R". List "spec" in your attribs file, and  
"gnetlist -g bom" will pick it up. So, make up an "instructions"  
attribute if you like.

Rough edges:

The tools complain about empty attribute strings, and make them  
difficult to create. Why? An empty string is a perfectly good  
attribute for some purposes.

Unknown attributes for a symbol instance show up as "unknown" in the  
BOM. Sometimes this is wanted, others not, especially in the case of  
custom attributes. This is another place where the project symbol  
directory approach comes to the rescue, because your project's  
symbols can contain defaults for your project's custom attributes,  
saving you from having to attach one to every instance.

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




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