Re: gEDA-user: finding shorts with gschem

[David Griffith <dgriffi@xxxxxxxxxxxxx>]

On Mon, 4 Feb 2008, Stuart Brorson wrote:

> > I did "grep -Ri vdd *" in the base directory of symbols.
> >
> > I noticed the "net=Vdd" thing, but in connection with something weird in
> > 4000/.  All of these symbols include a "net=VDD:??" statement.
>
> Does anybody use 4000 series CMOS anymore?

They're the 4016 (Quad analogue switch) and the 4052 (Dual 1/4 CMOS MUX).
Can you can suggest suitable 74xx series equivalents?  I'm working from a
10-15 year old schematic.

> But no matter.....  these net= callouts are attaching the net VDD to
> pin ??? IIRC.  I'm not sure what this would do to your netlist if you
> put one of these in your schematic and tried to netlist it.  Nothing
> good, I suppose...
>
> Your best bet is to fix this callout if you are using a 4000 series
> part.

"fix this callout"?  What do you mean?

> > This created an interesting problem with power/vdd-1.sym which has
> > "net=Vdd:1". These statements are not case-insensitive.
>
> If you are using the vdd-1.sym symbol in your design, then this
> attribute is creating a global net called Vdd, whether you want it or
> not.   If you want this, that's fine.  If not, then you need to change
> the name of the net to your desired netname, e.g. "net=mynetname:1".

Right, but there was the bizarre effect of some object containing
net=Vcc:? and net=Vdd:? somewhere, but disappearing when the Vcc and Vdd
symbols were not used.  That made me suspect there's a problem in the
interpretation of the symbol files, not in the symbols themselves.

> > Now, in retrospect regarding the request for manual critique, I think
> > there ought to be a chapter specifically on the proper use of symbols in
> > power/.
>
> You're likely doing it right.  The problem is that some of the symbols
> have junk in them which doesn't belong.  This is an issue with heavy
> symbols.  Caveat Emptor.

Ah...  So perhaps I should ask for write access to the CVS to go through
and fix this?  There are loads of other goofs I keep stumbling over in the
standard symbol set, which is part of the reason why I started making my
own.


-- 
David Griffith
dgriffi@xxxxxxxxxxxxx

A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
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