[gta02-core] To focus, or to re-focus ?

Werner Almesberger werner at openmoko.org
Thu Feb 18 12:59:04 CET 2010

?lvaro Lopes wrote:
> Sure, I'm not saying we ought ot do it, but some third party might.
> My point is - are *we* to use these prototypes for anything ?

You should be able to use it like any GTA02, except with faster
graphics. Plus, you could brag about having co-designed it :-)

> For example, changing CPU and display driver.

Which CPU ? What else besides the CPU chip would have to change ?
Would this significantly increase the design risk ? Can it be
sourced in quantities of 20 units and if yes, at what price ?
Does it come with stacked memory or does it need external chips ?

I think changing the CPU is too risky, even for a very similar
chip. Even the difference between 2442A and 2442B would be
dangerously large. If the CPU change requires a separate board
spin, the whole "building a phone on a shoestring" plan falls
apart quickly.

> And maybe add some
> room inside for attaching a custom small PCB

This brings us to the point of being able to make case changes.
We don't have this ability yet. People have talked about it a bit,
but I haven't seen anything happen. I don't know why.

> (we should have a bit of space right now).

Hmm, we'll see. Our PCB will be simpler and it'll be the first
layout of such complexity for probably all of us, so we may need
a bit more generous component spacing. Also, the modem does
actually get larger.

> True. But we can start layout with what we have, or cannot we ?

We're very close. We should at least first fix the components we
can be sure will be missing, namely:

cd svn.openmoko.org/trunk/gta02-core/bom
make optimist
make show-missing

We can ignore ATR0635, PCF50633, and WM8753, since they're all
or nothing anyway. But the rest still needs replacing (with parts
that can be readily sourced, e.g., that Digi-Key stocks) and some
of the footprints may change as a consequence.

You can also to the same with "make pessimist". If you add a
replacement we don't need in the end, the BOM system will know
to ignore it because the original part is cheaper.

> If you are referring to software, yes. But hardware is closed.

Exactly my point :)

> My worries are design becoming so obsolete that it does not fit any
> concrete purpose.

That depends a lot on what comes next. If a similar design were
to be built based on gta02-core, many things would stay the same.
For something radically different, there would be lots of changes,
of course.

> Like designing an open hardware vacuum-tube television. It's fun, but
> won't fit any practical use.

Don't underestimate the value of experience :) The tube may not
be of much practical use, but you'll still learn a lot about
making TVs :-)

> Heh :) That's why I decided to buy one, and not build my own :P

I bought as well, but there's a bit of stuff that needs fixing.
And if IT projects are rife with budget and schedule overruns,
then there's a whole new world waiting in remodeling projects :-(

Anyway, workers are arriving, time to plan the mistakes to be made

- Werner

More information about the gta02-core mailing list