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SubjectRe: [PATCH v2] lis3lv02d: Add STMicroelectronics lis331dlh digital accelerometer
12bit it IS then. :-)
LGTM. +1.

On Thu, Aug 23, 2012 at 4:45 PM, AnilKumar, Chimata <anilkumar@ti.com> wrote:
> Chinmay,
>
> On Thu, Aug 23, 2012 at 15:53:10, Chinmay V S wrote:
>> > Note from datasheet, "1LSb=4g/4096 at 12bit representation,
>> > ±2g Full-scale"
>>
>> Precisely my point. All the datasheet says is :
>> 1. It is +/-2G mode --> so Numerator is 4G.
>> 2. We are using 12bits --> so Denominator is 2^12 = 4096.
>>
>> There is no clear reason/justification as to why 12bits was chosen in
>> the first place. At this point unless someone from the
>> design/original-driver team actually confirms why the 12bit
>> representation was chosen, it is all conjecture on our part.
>>
>> If you have the actual LIS331DLH hardware, can you verify if the lower
>> 4bits do actually contain any data (or are they always zero). This
>> will help us decide whether to use them(16bit mode) or discard
>> them(12bit mode)?...
>>
>
> This is the outdata of accelerometer
>
> root@am335xevm:~# cat /sys/devices/platform/lis3lv02d/position
> [ 16.323852] lis3lv02d: hi 0x1 low 0x50 val 0x15
> [ 16.329742] lis3lv02d: hi 0x0 low 0x0 val 0x0
> [ 16.335052] lis3lv02d: hi 0x3e low 0x50 val 0x3e5
> (20,0,973)
> root@am335xevm:~# cat /sys/devices/platform/lis3lv02d/position
> [ 25.777343] lis3lv02d: hi 0x2 low 0xa0 val 0x2a
> [ 25.783203] lis3lv02d: hi 0xc1 low 0xf0 val 0xfffffc1f
> [ 25.790130] lis3lv02d: hi 0xfd low 0x50 val 0xffffffd5
> (41,-969,-41)
> root@am335xevm:~# cat /sys/devices/platform/lis3lv02d/position
> [ 47.607330] lis3lv02d: hi 0xc0 low 0x60 val 0xfffffc06
> [ 47.613464] lis3lv02d: hi 0xfd low 0x90 val 0xffffffd9
> [ 47.619934] lis3lv02d: hi 0x2 low 0x40 val 0x24
> (-994,-38,35)
>
> Lower nibble always "0"
>
> Regards
> AnilKumar

--
regards
ChinmayVS
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