accelerometer jitter

Steve Mosher steve at
Sun Sep 21 05:05:19 CEST 2008

Have a look at this might help.

Note, we dont use a freescale accel, so some things may be different but 
you'll get the basic idea.

Joel Newkirk wrote:
> On Sat, 20 Sep 2008 17:36:00 -0400, "Michael Fisher" <desnotes at>
> wrote:
>> 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
> piped)
> 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)
> j
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