My accelerometers aren't calibrated.

Fox Mulder Quakeman1 at
Wed Nov 26 11:08:27 CET 2008

Mateusz Kondej wrote:
> Hi,
> I think that accelerometers in my FR aren't calibrated or driver doesn't 
> work properly. For example, if I use script form 
>, I got this 
> data:
> 54 -18 -1062 1063
> 54 -18 -1062 1063
> 36 -18 -1062 1062
> 54 -18 -1062 1063
> 54 -18 -1044 1045
> 36 -18 -1080 1080
> FR is laying on my table, screen to bottom. So it should return gravity, 
> 981 cm/s^2. But It returns similar values but it's too big for me.
> How to get properly results from accelerometers? Eventualy How to 
> calibrate them?

I'm wondering, why the LIS302DL kernel driver returns 16bit values for
each axis. Because the sensor itself has only 8bit resolution for each
axis. The next question is if the returned values are normalized to
"g * 10^-2" or just upscaled raw values (which makes no sense). Because
1g in 8bit would be ~64 if the sensor is set to +-2g range (which can be
changed to +-8g range within the sensor).
When the returned values are representing "cm/s^2" than you are right
that the z-value is a bit off.
But i can't find any related information about how to interpreted the
returned x/y/z axis values on the wiki page.


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