digital compass sensor (instead of second accelerometer)

[Piers Titus van der Torren]

Hi,
I'm new to this list, so let's start with saying that I find it fantastic
that such a fantastic device is developed is such a beautiful way.

I have been following the news on openmoko for some time, and have been
thinking on possible uses and improvements too.
Besides some things that can be developed separately relatively easy I was
thinking about the possible uses of a digital compass,
see http://wiki.openmoko.org/wiki/Wishlist_-_Hardware:_Digital_compass

In short: besides the obvious uses like aligning maps to the terrain and a
compass, a compass makes a nice addition to the
accelerometer, since the absolute rotation can then be measured in 3D.

I think it would be nice if a compass is added as standard feature, since
many applications can make use of it. (It would also be hard to
modify all these application so users that add a compass chip themselves can
fully benefit from it)

The AK8973 seems a very nice sensor, only hard to find when you don't speak
japanese: http://www.akm.com/datasheets/ak8973_E-01.pdf
The predecessor of it, the ak8970N, costs $5.24 in 25k+ quantities, see
http://www.akm.com/press_release/ak8970Nwpr.pdf
The Honeywell HMC6352 also is nice, only probably too expensive (seen it for
$22 in 1k order size in an online shop):
http://www.ssec.honeywell.com/magnetic/hmc6352.html

Also I was wondering, now that the GTA02V2 is finished, what are the
accelerometers that will be used? Is it still the LIS302DL?

Another thing I'm curious at is what the thoughts behind two accelerometers
are. It seems more useful to embed one better accelerometer
like the LIS3LV02DL than having two LIS302DL's. The price doesn't seem to
differ much, only it's double the weight and power usage.

Greetings,
Piers (PTT on the wiki)
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