Accelerometer in next hardware revision?

openmoko at openmoko at
Wed Jun 6 18:29:29 CEST 2007

> On Tue, Jun 05, 2007 at 10:58:54PM +0100, Rene Mayrhofer wrote:
>> What sampling rates are you aiming at? I'm currently working with the
>> Nokia
>> 5500 purely because it has an embedded 3D accelerometer as well. Quite
>> unfortunately, the sample rate is limited to somewhere in the range of
>> 30Hz,
>> which is rather low for what I'd like to use it for.
> Right now we're looking at the LIS302DL from ST.  It's < 1mW power and
> has selectable +/- 2 or 8g full-scale, and you can runtime-configure the
> sample rate to either 100Hz or 400Hz. - a moderately
in-depth look at what accelerometers can do in a phone.
It is _not_ finished.
I intend to add a little dancing phone, to indicate what the phone thinks
its position is, with two accelerometers.

>From the first online vendor I found - I found that at quantities of
around 1K, the ST part is about $3 more than the AD one.

And it has only 7 bits of resolution. This basically makes it useless for
some other apps - for example, in a car-holder, with a few more bits, you
can do useful dead-reckoning for a period of up to 30s or so.

I note that the PIC16F677 is about $1.3 in 1000s, quite small - 4*4*1mm,
and  has 12 10 bit A/Ds in, as well as a SPI interface, and very low on
power, when used at ~1Mhz. (the two parts together use about 20% more
power than the ST part)

It could also have a role if it could switch down to 32KHz, in which case
it could do interesting things monitoring other devices in the phone.
For example, there are plenty of A/Ds, and GPIOs, which could listen to
the mic, ...

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