Re: gEDA-dev: multiple schematic in a hierarchy

[Steve Meier <smeier-at-NOSPAMalchemyresearch_dot_com>]

sounds like the joke about economists.

You know if you ask three economists their oppinion you will get at
least four answers.

Geda does support hierachy on a number of levels.

For the schematic to circuit board design it has limited but functional
hierarchy.

gschem/gnetlist/pcb can support

a case where you have the toplevel schematic "A"

Inside A there is a symbol which has a schematic source file associated
with it Call this symbol "B"

"A" can have multiple instances of symbol "B" within in it 

Thus "A" can have two instances of "B" but each one placed on page "A"
must have a unique reference designator (refdes) such as "S1" and "S2".

Siliarily there can be a third symbol "C" again with its own schematic
and "C" can be placed several times on the schematic "B" each instance
of "C" should have a unique refdes.

Thus if you have 3 instances of C you could set each of their refdes to
S3, S4 and S5.

When you run the netlister for pcb you will components on Schematic "C"
e.g. u1, u2 and u3. in the netlist as

S1/S3/U1
S1/S3/U2
S1/S3/U3
S1/S4/U1
S1/S4/U2
S1/S4/U3
S1/S5/U1
etc.

similarily you would find 
S2/S3/U1
S2/S3/U2
S2/S3/U3
S2/S4/U1
S2/S4/U2
S2/S4/U3
S2/S5/U1
etc.

and pins from S1/S3/U1 can be connected to pins on S2/S4/U3

What doesn't work well for pcb's is hierarchical bus netlisting. At
least in stock geda. Though I have recently learned that stock geda can
do a version of hierarchical netlisting for verilog.

If this is what you are asking for and you need aditional help. Please
ask. There is a very good group here ready and willing to kabitz. If you
don't mind the four or more different oppinions.

Steve Meier


On Fri, 2008-01-11 at 16:23 -0500, Stuart Brorson wrote:
> Tim,
> 
> Thanks for your e-mail!
> 
> > I'm a part-time developer of kicad and a part-time pcb designer.  My most
> > recent project has a lot of duplicated circuitry in a three-level hierarchy,
> > something which kicad does not support very well.  Kicad allows a hierarchy,
> > but it does not allow different component references on different instances
> > of the same schematic. e.g. the hierarchy is something like this
> >      A
> >   B    B
> > C  C  C  C
> > where each of the different C sheets originates from the same file etc.
> 
> GEDA does not support this as of now.  Several proposals have been
> floated to implement this feature into libgeda (the .so which
> underlies the various tools).  In fact, some of the developers in the
> UK have presented UML drawing showing a new scheme for libgeda's data
> structures which would support this type of hierarchy.
> 
> > I've spent the last two weeks trying to add this feature, but it is not easy
> > :(  does g-EDA already have this feature?  I'll convert my schematics, if
> > so.
> 
> Don't convert your schematics yet.  However, if you talk nicely to the
> UK Peters, they might be interested in joining forces with you and
> implementing some of their proposed ideas.  Personally, I'd welcome
> that!
> 
> Cheers,
> 
> Stuart
> 
> 
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