Re: gEDA-user: Database on symbols, footprints and other (was "Re: gattrib")

[Armin Faltl <armin.faltl@xxxxxx>]

A bit more reading and thinking reveals a problem with current gpart:

To express the many-to-many relation between parts and symbols it uses
a table called "device". This is fed by the infamous device attribute
in the symbol libraries. There's nothing wrong in the theory of DB-design
with it, but the indiscriminate use of this attribute in the symbol-libs
waters the use of this design down to uselessness.

While sacrificing the ability to attach more than one symbol to a part
by directly referencing the symbol in the part, my schema avoids this
problem. To use it, one has to bypass the device thing and enter a correct
relation. This would have meant no drawback for me, since I rarely see
a need to use more than one symbol per part personally. And others will
see this different.

The flexible way to fix this, is to go the way of gpart and use the
device table correctly by either not feeding from the current symbol
libraries of fixing the device attribute there.

Example that bit me on 1st chance:
there is a US and EUR variant of the resistor-varible-?.sym so both
will have zealots in favour. Both use a random pinout and don't
show, which pin is which in the schematic. Both say
   device=RESISTOR_VARIABLE
and here is the problem: of course the tap on my physical potentiometer
is at pin 2 and so it is in my selfmade footprint, while in the symbols
the tap is of course at pin 3.
To get this right in the database one has to use something like
   device=POTENTIOMETER_T2
to show where the tap is in the symbol, so it is impossible, to
connect a device=POTENTIOMETER_T3 with my footprint.

Of course it was easy to fix this with a scalpel, verowire and
a soldering iron ;-) And later on with a selfmade symbol that is
more elegant than the others anyway...

Regards, Armin


Armin Faltl wrote:
> Thanks for the hint.
>
> I installed git on my machine to get this
> Then I searched for references on the web, since the README is a
> oneliner stating it's own existence.
>
> After having found this http://www.geda.seul.org/wiki/geda:gparts_dd
> I see now, that I reinvented the wheel with small differences.
> No mention of gparts can be found in the master documentation of geda
> http://geda.seul.org/wiki/geda:documentation
>
> I won't try to compile it now, but the table diagram looks promissing.
>
> Regards, Armin


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