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LSM9DS0 and LSM9DS1 acceleration sensitivity confusion

Question asked by Mark Williams on Mar 13, 2017
Latest reply on Mar 13, 2017 by Miroslav B

All the sensitivity values for the acceleration fit within 16 bits, however  ±16 g does not.

 

Let’s use FS ±2 g as an example sensitivity level.  As the range is -2 to +2, this would be a total of 4g.  Or 4,000 Milli-Gs.
The output is 16 bits. 16 bits equals 65,535.   This means we can get 65,535 different readings for the range  between -2 and +2. (or -2,000 MilliGs and +2,000 MilliGs)

 

4,000 MilliGs / 65,535 = 0.061

 

0.061 is what is seen in the datasheet for ±2 

 

here are the values for all sensitivity levels;

 

±2  = 4,000 MilliGs / 65,535 = 0.061

±4  = 8,000 MilliGs / 65,535 = 0.122

±6  = 12,000 MilliGs / 65,535 = 0.183

±8  = 16,000 MilliGs / 65,535 = 0.244

±16  = 32,000 MilliGs / 65,535 = 0.488

 

 

The only one that doesn't match up with the datasheets for both LSM9DS0 and LSM9DS1 is for ±16.  The calculations above show 0.488, but the datasheets have 0.732

 

Can someone please explain why this is so?

 

 

 

 

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