[gta02-core] Footprint editor

[Werner Almesberger]

Patryk Benderz wrote:
> > - review the Telit GE865 circuit symbol, see page 13 of
> >   http://people.openmoko.org/werner/gta02-core/gta02-core-expanded-all.pdf
> What do you mean by "review" ? What does "review" mean exactly?

Hmm, I should explain that in GETTING-STARTED. For circuit symbols,
reviewing means to check:

- that the pin names (GPIOx, nRESET, etc.) match with the data sheet
  (as an exception, we correct inconsistencies and make sure inverted
  pins have a sensible name - usually nSOMETHING)

- that pin/pad numbers match those in the data sheet

- that the drawing is correctly done and conveys the purpose of the
  component

- that pin types match what the data sheet says

- that permanently inverted signals have a circle either inside the
  symbol or at its edge (examples: X74X1G00_5 and XRT9711_BD_5 in
  expanded/usb.sch)

It's also a good idea to have a look at Openmoko's GTA02 design (if
the same component it used there) and check if there are any
significant differences to what the data sheet says. If yes, report
them to the list.

> > - or maybe you want to try the bleeding edge of buggy new software ?
> >   Then you can try to make new footprints with fped (or at least
> >   find bugs that prevent you from doing this ;-):
> >   http://svn.openmoko.org/trunk/eda/fped/README
> This looks pretty easy, maybe i should start with this?

Yeah, I think you'll be the first user apart from myself. I already
made a number of footprints, which you can use as a reference. They
are in gta02-core/modules/

The key to making good footprints with fped is to get the frame
hierarchy right. The root frame is usually a good place for most
non-iterated variables. If the footprint is simple, you may also
put the placement of pins there. I put the actual pads, the outline,
and the keep-out area into separate frames. Iterations sometimes
need their own frame. Measurements automatically go to the root
frame.

- Werner