Re: gEDA-user: pcb refdes name restrictions?

[Peter Clifton <pcjc2@xxxxxxxxx>]

On Mon, 2006-10-30 at 13:59 +0000, Peter Baxendale wrote:
> Another dumb question. I teach a class of undergraduates about ECAD and
> this year abandoned commercial tools in favour of geda. Students being
> students, they tend to try things I wouldn't think of doing. Today, a
> couple of them decided to be creative and on their schematic used names
> like "CONNpower" and "CONNsignal" for refdes values. Whilst I thought it
> unconventional and probably inadvisable, I couldn't offhand see why they
> shouldn't do that.
> 
> Gsch2pcb happily produced a netlist and pcb file which both looked fine,
> as far as I could tell. But when loaded into pcb, optimising the netlist
> causes error messages such as "Can't find CONN pin 4 called for in
> netlist".
> 
> So does pcb require that all reference designators be in the form of a
> string followed by a numerical value? If so, are there any other refdes
> restrictions I should know about? Given time, they're bound to find
> them...
> 
> Thanks,
> PB

Any lower case suffix is ignored. This is so you can, for example, place
4 discrete NAND gates on the schematic called U1a, U1b, U1c and U1d, and
they will netlist into a single footprint / component, U1.

(The NAND symbols are "slotted", you set the 4 gates to a different slot
number - with the "slot" attribute, and they will each netlist to the
correct pins in the final package.)

So... don't use lowercase suffixes, also:

Don't use the hyphen character "-", in the refdes, as it upsets the M4
macro language used to process generating the footprints. (I think "_"
is ok.

I'm not sure of any other restrictions. Spaces are probably unwise " ",
but I've not tested that.

Regards

-- 
Peter Clifton

Electrical Engineering Division,
Engineering Department,
University of Cambridge,
9, JJ Thomson Avenue,
Cambridge
CB3 0FA

Tel: +44 (0)7729 980173



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