accelerometer jitter

Joel Newkirk freerunner at
Sun Sep 21 01:44:34 CEST 2008

On Sat, 20 Sep 2008 17:36:00 -0400, "Michael Fisher" <desnotes at>
> On Sat, Sep 20, 2008 at 4:07 PM, Joel Newkirk <freerunner at>
> wrote:
>> I wrote a short shell script to repeatedly take the raw output from one
> of
>> the accelerometers
> (/sys/devices/platform/spi_s3c24xx_gpio.1/spi0.1/dump)
>> and massage the data to output X,Y,and Z-axis readings in decimal, -128
> to
>> 128.

> As a bit OT but since you have gone to the trouble of developing the
> script,
> could you run a test while driving/riding in the car and post what the
> readings might be? I was thinking of the possibility of having the FR
> determine if it was in a moving car or not.
> Mike
> --
> Michael Fisher
> desNotes at

No problem, I'll alter the script to intersperse timestamps and take it for
a ride tomorrow.  It's dumping samples about once per second ATM - I'd
initially included a 'sleep 1' command then commented it out since the loop
execution ended up taking about 1 sec anyway.  (chains of cat/grep/sed/cut

The one caveat is that I don't have a good mount for it in the car - for
the requested test I'll just lay it on the floor on the passenger side and
note the physical orientation.  (more OT than this request, I found out
that the rubberized surface on the back of the Freerunner is essentially
non-stick if you try to lay the Freerunner on a Handstands StickyPad - I've
had one of those on my dashboard for years, always kept my cellphone and
Zaurus there even on a sloped dashboard, but the Freerunner won't stick to
it even on the flat dash in my new car)


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