Re: gEDA-user: slots, etc.

[Ales Hvezda <ahvezda@moria.seul.org>]

>A couple questions about multi part components:
>
>* Does a schematic level attribute override a symbol attribute? For example, t
>he
>lm339-2.sym has a net=V+:3 net but I want it to be net=Vss:1. Can I just add
>net=vss:1 to the schematic?

	Yes, a schematic level attribute overrides a symbol attribute.
However the net= is a little special.  Suppose you have a symbol which 
has net=GND:7, but you really want that net to be called AGND:7, then you
can attach a schematic level net=AGND:7 and override the netname.  

	However, if I read your question correctly, you want to override
both the netname and the pin number of net= created net?  I don't think
that is currently possible; only the netname can be overridden.  It would
be best if you created a local symbol for this.  Please clarify your question
if I have misunderstood. 


>
>* How are slots associated with the same package? For example, can I add a
>footprint=SO14 to the symbol at the schematic level or do I have to add it to
>the symbol?

	Slots are typically associated with instanciated symbols
(components) which have the same refdes.  In otherwords, all components
which have the same refdes are typically in the same physical package.
Homogenous components (all slots look the same but only differ in pin
numbers) use the slotting mechanism (slot=?), while heterogeneous
components have different graphical representations and do not use
the slotting mechanism.  Back to your question, I'm not quite sure I
understand it.

	If you have a homogeneous mult-slot component and you have one
slot which has a different footprint= attached at the schematic level,
the netlister will be confused.  Which footprint= is the one you really
want (the one inside the symbol or the one attached to one of the slots)?
To solve this, you need to attach the footprint= attribute to all slots,
which is quite error prone.

	I believe the same thing would happen if you had a heterogenous
component.  The netlister will not know which footprint= attribute to use
if it is in more than one place (and three possible places are:  inside
a symbol, outside of a symbol, and attached to only one part of the
heterogenous component).

	Please clarify your question if this does not help.  Thanks.

								-Ales