On Wed, Aug 22, 2012 at 22:24:10, Chinmay V S wrote: > > 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 > > Had been through the application note earlier. The table5 (on page 12) > that you refer to, does NOT contradict either 12/16bit, as in all the > examples the lower 4 bits are zero. So i don't see how one can assume > from these examples that for +/-2G they one should consider 12/16bits. > A nice side-effect of using 12|13|14bits for +/-2|4|8G is that the > values returned by the driver are in mG in all the 3 modes. > > > 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. > > Going through the code of this driver i can see what you are talking > about. Depending on the full-scale-range the device is being > configured for, the number of bits used to represent acceleration in > the driver is changed. > > Again judging from the code, the driver is always returning > acceleration at a constant accuracy i.e. 1mG in all the 3 modes > (+/-2|4|8G)i.e. > +/-2G is mode means value can be anywhere from +/-2048mG, > (requiring 12bits.) > +/-4G in the range of +/-4096mG, requiring 13bits. > +/-8G i.e. +/-8192mG, requiring 14bits. > > Was this done... > > a. ...because LIS331DLH's theoretical MAX accuracy is ~1mG > If yes, then using 12bits is fine. >
Note from datasheet, "1LSb=4g/4096 at 12bit representation, ±2g Full-scale" >From this I understood that ±2G full scale value is 12 bits. That is one more reason to take 12bit value. Regards AnilKumar -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
