Hi,

I am working on a project that is using LIS2DH sensor for measuring the acceleration along the X,Y and Z-axis. I have configured the IC as per the following configurations:-

1>Using the 8-bit resolution to capture the data of X,Y and Z-axis.

2>we have enabled the low power mode of this sensor.

3>We have set the ODR as 50 Hz.

when we set the full scale value as +/-4g, then we get the default value for OUT_X register as 0, OUT_Y register as 0 and OUT_Z register as 30 since there is a constant acceleration along Z direction with magnitude of 1g due to gravity when the device is static. Since we are using 8-bit register the range can be vary from -128 to +127, so the default magnitude that can be achieved is 32*30 (1LSb = 32mg as per data sheet) i.e. 0.96g which is approximately equals to 1g.

When we set the full value to +/-8g then the default value when the device is static along the Z-axis is 15 so 15*64 (1LSb = 64mg as per datasheet ) i.e. 0.96g which is approx equals to 1g.

And when we set the full scale value to +/-16g then the default value when the device is static along the Z-axis is 5 so 5*192 (1LSb = 192mg as per data sheet) i.e. 0.96g which is approx 1g too but here when we calculate the full scale value by multiplying 192*127(because maximum value that can be set in 8-bit signed register is +127) i.e. 24.34g which is much far greater than the set full scale value i.e. +/-16g but in the above two cases i got the correct full scale values FS=+/-4g (127*32) i.e 4.064g and when FS=+/-8g (127*64) i.e 8.1g, so why i got the calculated full scale value much above the set full scale value i.e +/-16g ?

The datasheet and the section that is refer here is "LIS2DH MEMS digital output motion sensor:ultra low-power high performance 3-axis “femto” accelerometer" and section 2.1 "Mechanical characteristics" respectively.

Hello,

I believe the answer is the same as to my similar question to a magnetometer scale asked here: https://community.st.com/thread/40903-lis3mdl-data-interpretation#comment-157266 (check the answer below).

Long story short, according to the Mechanical characteristics section you mentioned is the provided range

typical(and also the sensitivity is stated astypical), so the sensor is not guaranteed to give you the full proportional output.