Re: gEDA-user: Bug report for renaming slots [Was: Re: gEDA on windows]

[Peter Clifton <pcjc2@xxxxxxxxx>]

On Mon, 2009-01-12 at 17:26 -0800, Joerg wrote:

> I am not a programmer but one method I could imagine would be to have a 
> switch that disallows splintering up slotted devices, meaning the 
> devices can get other refdeses but it must be the same for all slots of 
> a device. It's the same for transistor arrays when temperature-tracking 
> will be lost if slots are mixed up. I believe it would be ok to do such 
> disallow or allow as a general setting, for the whole schematic.

Thanks for the suggestion.


Actually, your idea has got me thinking more about how we handle
attributes on slotted parts, and the possibility that they could in some
way be treated as an aggregate component for the purposes of attributes
other than "slot=".

Your example quoted suffixed refdes, such as U1A, U1B etc. I know that
is often standard practice in some tools, however I gave up on this with
gEDA because it causes confusion at the netlist stage.

Whilst PCB drops lowercase suffixes, not uppercase - gnetlist doesn't
drop any suffixes. I tried to teach it to drop lowercase refdes
suffixes, but that broke some hierarchy infrastructure (which uses the
refdes of an IO marker component) so it had to be reverted.

As a workaround, the refdes= could be hidden, and a "label=" or similar
attribute could be used on the schematic if you wanted the suffixes.
Knowing me though, I'd just get those out of sync with the refdes and
get myself lost debugging the issue.

Naturally though, if we had any slot-specific label, or refdes, that is
another class of attribute which couldn't be shared as being common to
group of slotted parts.


Whilst we're almost on the topic:

There is a bug in gnetlist, that the slot it sees first determines which
attributes are discovered for a particular refdes. (Not the union of
attributes attached to all slots).

If you put footprint= on slot #1, but the netlister picks up attributes
from slot #2, and doesn't find your footprint= attribute.

It would appear from my own testing, that the first symbol encountered
in the schematic file with a given name is the one which determines
attributes. This is why I recommend to people that they should set the
"footprint=" attribute on all slots when using slotted parts.

I'm planning to do some work on gnetlist / netlisting in libgeda for the
1.8 series, so I'll see if I can address this issue during the next
development cycle.

Regards,


-- 
Peter Clifton

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

Tel: +44 (0)7729 980173 - (No signal in the lab!)



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