Re: gEDA-user: multi-part symbols [was: OGDI]

[John Doty <jpd@xxxxxxxxxxxxx>]

May I make an alternate suggestion here?

The "slot" mechanism is for identical internal subsystems within a  
part. I propose keeping it that way: I think any attempt to extend it  
to heterogeneous internal subsystems is likely to make a confusing  
mess. It's already confusing enough!

Instead I propose adding the concept of "subdevice", supported by  
attributes "subdevice" and "others". For example a 7400 gate symbol  
might have the attributes:

device=sn7400
numslots=4	(with the usual other slotting attributes)
subdevice=1
others=sn74pwr14

There would be a generic power symbol for a 14 pin TTL package with  
attributes:

device=sn74pwr14
numslots=0
subdevice=1
footprint=DIP14

Thus a full 7400 package would be represented by four sn7400  
instances plus one sn74pwr14 instance. The "subdevice=1" attribute  
without "others" would tell gnetlist to warn the user if the symbol  
is an orphan without other subdevices with the same refdes (this is  
for generic subdevices like the sn74pwr14 where the other associated  
subdevices may vary). The "subdevice=1" with "others" would tell  
gnetlist specifically what other subdevices are needed to make a  
complete device. If any is missing, gnetlist could issue an  
appropriate warning.

Having the footprint associated with the generic power subdevice in  
this case would make it easier to change package technologies for a  
whole family: just make up a new symbol with device=sn74pwr14 and the  
correct footprint.

John Doty              Noqsi Aerospace, Ltd.
jpd@xxxxxxxxxxxxx