Re: gEDA-user: Very heavy symbols

[Carl Denzen Van <carl@xxxxxxxxxxxx>]

Thank you all for the tips! It is getting clearer for me.
Werner wrote:
"I'm using BCE as pinnumber attributes as long the footprint of the  
device (transistor) is not defined. Thus it's easy to replace them  
when adding a footprint."

I am using npn-2.sym for a BDX33 in TO220.
What is the easiest way to replace them (the pinnumbers in my  
schematic/symbol) when adding a footprint? I did not find how to do  
it with gattrib. So I created a sed script to patch my netlist file,  
but I hope there is an easier way. The geda documentation is not very  
clear about this point. This is really important for me to get  
further with my project.

And I have some wild ideas about symbols. Please give some comment on  
this too.
I have seen symbols with footprints and alternate footprints.  
Wouldn't it be a good idea to have "very heavy" symbols that  
incorporate the definition of many footprints, and you can select one  
of them with p.e. an attribute choose_footprint=TO220_EBC? The symbol  
would look like this:

device=NPN_TRANSISTOR
alt_footprint TO220_ECB
{
footprint TO220
gschempinnumber "E"=footprintpinnumber "1"
gschempinnumber "C"=footprintpinnmber "2"
gschempinnumber "B"=footprintpinnumber "3"
}
alt_footprint TO220_EBC
{
footprint TO220
gschempinnumber "E"=footprintpinnumber "1"
gschempinnumber "B"=footprintpinnmber "2"
gschempinnumber "C"=footprintpinnumber "3"
}
alt_footprint TO126_EBC
{
footprint TO126
gschempinnumber "E"=footprintpinnumber "1"
gschempinnumber "B"=footprintpinnmber "2"
gschempinnumber "C"=footprintpinnumber "3"
}

Advantage:
-you have very little number of symbols, which are easier to maintain  
(compared to heavy symbols)
Disadvantages:
- the file definition changes (documentation must be updated)
- gsch2pcb must understand the new file format

Maybe I am not the first one to propose this idea, but I didn't find  
it anywhere yet.

Carl van Denzen


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