RE: [PATCH v2] lis3lv02d: Add STMicroelectronics lis331dlh digitalaccelerometer

[AnilKumar, Chimata]

On Wed, Aug 22, 2012 at 16:09:22, Chinmay V S wrote:
> Hmmm. Interesting. As i understand LIS331DLH provides 16bit data
> irrespective of the full-scale/sensitivity configuration. Hence we
> could effectively map +/-2G to +/-32768(signed 16bit 2's complement).
> According to the current-patch right-shifting the register values by
> 4(i.e. reducing 16bit --> 12bit) will mean that we lose accuracy by
> ~1mG.
> 
> Clearly this will NOT affect use-case like display-orientation in
> smart-phones, but surely medical and industrial applications WILL
> benefit from the additional accuracy by utilising the entire 16-bit
> resolution provided by LIS331DLH hardware.
> 
> I went through the LIS331DLH datasheet/application-note from
> http://www.st.com/internet/analog/product/218132.jsp and i'm a bit
> confused from your statement about +/-2G being 12bit data. Nowhere is
> it mentioned that LIS331DLH provides +/-2G|+/-4G|+/-8G as 12|13|14 bit
> data respectively. Then again i might be wrong...
> 

Look at this application note which talks about the outdata values
for 2G range (page 12/31) http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/APPLICATION_NOTE/CD00215823.pdf

Corresponding to the 4G and 8G I got the details form older
patches (SHIFT_ADJ_4G and SHIFT_ADJ_8G).
http://driverdev.linuxdriverproject.org/pipermail/devel/2010-November/009685.html

We can easily interpret number of bits for 4G and 8G from 2G
information.

Thanks
AnilKumar
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