Mail Archives: geda-help/2013/01/24/11:32:59
On Thu, 2013-01-24 at 15:09 +0100, Jakub Klawiter wrote:
> >
> I'm not sure about correct naming so one more question. So it is possible
> to add thermals (by THRM tool) only to round shaped pin pads, not for e.g.
> oval/square ones?
> Should I remember anything else to define pin which will work with that
> THRM tool to add thermals?
>
>
In the newlib footprint files (*.fp) we have Pad and Pin statements --
Pads basically for SMT elements, Pins for Through-Hole elements. Pins
with oval copper are built with a round pin overlapped with a Pad with
the same name/number. For every drill hole in your PCB board you can
place a thermal, only for Pads for SMD elements you have to draw a
line/trace segment to the surrounding copper polygon. (Maybe it is
possible to extent the PCB source code to allow thermals for Pads -- I
can not remember the reason why we currently have none. There is reason,
it was mentioned on this list long time ago.) We have even different
shapes of thermals for Pins, try to click multiple times with the
thermal tool selected while holding down the SHIFT key.
> > Unfortunately that describes not the latest format -- I think we can use
> > units like nm in footprint definition now, I will try to adapt that text
> > when I have some spare time...
> >
> So it is possible to use nanometers? The footprint i like to create is
> metric sized so using metric units will give me „nice numbersĄ. I'm trying
> to google about that but found only some postings from mailing list about
> patch added to the repository. Here:
> http://wiki.geda-project.org/geda:pcb-quick_reference#pcb_units i found
> something about metric units but cannot find any information how can I
> define metric units in footprint file.
> I know only about using mils and centymils defined by type of bracket in
> command.
> BTW if metric scale/nanometer unit is new here. What is the oldest release
> which is using it. The one I have here is:
> $ pcb --version
> PCB version 20110918
> is it ok? I know that there is newer one but it is not in ubuntu repository
> yet. I have newer one in my desktop computer at home.
>
>
Yes, you can use nm and other metric dimensions in current footprint
files -- that may be nice if you define footprints manually with an text
editor. Unfortunately I can not remember details -- it should be
described somewhere in the documentation/wiki -- I guess we have this
feature since about one year.
>
> > Older footprints where created by m4 scripts with parameters indeed, but
> > most people favorite the so called newlib footprints now, which are self
> > contained and do not depend on m4 macro processor. A lot of tools exist
> > to create footprints, some use textual description, some have graphical
> > front-ends.
> >
> :( it was IMO nice idea to create one file for e.g. that screw terminal
> connector which can be used for all of them. OK it's not possible so I'll
> try to write perl script to generate it for any number of pins.
>
If you are smart, you may try to invent new/extended footprint file
formats -- our current newlib format is not the ultimate solution, there
are some features missing, like keepout, silk or arbitrary text, maybe
additional information for 3D models. But of course such an extension is
a large, non trivial task, you have to think carefully about what is
useful, what is possible for gerber export, and you may consider a
common format for gEDA/PCB and KiCad. I am absolutely ignorant about all
that, sorry.
Best regards
Stefan Salewski
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