[gta02-core] Footprint editor

Werner Almesberger werner at openmoko.org
Fri Dec 11 01:50:37 CET 2009

Patryk Benderz wrote:
> Wow, I need to say I am impressed :) After reading this I feel like I
> could start helping this project... if I only was skilled in
> electronics :(.

Thanks ! Some basic knowledge of electronics helps indeed, but quite
a lot of inconsistencies can be spotted without being an expert.
Besides, it's a great learning opportunity :-)

> ++Schematics reviews should meet following requirements:

Ah yes, I first had the intro finish with things to check and the
sections had just the lists, but then I put intros there as well,
and so this doesn't flow anymore. I just added "things to check".

> 	- equivalence to the respective circuit in GTA02 (++documentation?),
> except if a change has been made through an ECN

You mean GTA02 documentation ? By and large, the schematics are the
(public) documentation. There are plenty more details in the mailing
list archives, but they're kinda hard to use as a general reference.

I added the URL of the GTA02 schematics.

> 	"- use of the same component references (R1014, etc.)" - what to do if
> adding/removing component? fill the gap which occured after removing
> some other resistor, or maybe take last: R(n+1) ?

Good point, that needs explaining as well. Reusing component references
would be extremely confusing. A R(last+1) rule would work, but one may
also choose R(last+k) to emphasize any differences. The original
schematics have holes in the sequences as well.

> 	"- there be no spaces between numbers and units" - I am not native
> speaker, but looks weird for me...shouldn't be "there will be no" or
> "there are no"?

Phew, I think I'll have to ask a native speaker to explain how exactly
this one works :-) But unless I'm horribly mistaken, it is equivalent
to "there shall be" or, weaker, simply "there are no".

> 	"- units of additional parameters and all units of components that are
> not R, C, or L, are written in regular SI or SI-like notation, e.g.,
> 17.6pF, 5.6Vac" - this might be confusing, as you show capacitor as an
> example, while a moment before you write to omit C...

I guess the example is a bit too compressed. What I meant was that
a component that's not a capacitor but that has a capacitance worth
specifying anyway should not omit the unit. For example, a TVS is
not a capacitor but it has a capacitance that's normally specified.

I've made the example more verbose and added also an example for a
mixed situation.

Ah, and I spotted a bug - we had varistors with 151 and 331 pF,
which should be 150 and 330 pF, respectively. I've corrected them.

> 3
> Layout
> ------

> To do. - you mean physical location of components on PCB?

Physical location of the components and the traces connecting them.
I.e., the part where the real fun starts :-)

- Werner

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