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NMale.1
NMale.1
Associate II
October 31, 2020
Solved

What is the ZERO offset value of LIS3DH after Factory Calibrated?

HI,

After Factory calibration of LIS3DH accelerometer, what are the range of values given by the accelerometer( Selected 12 bit OUTPUT). I am getting 20-30 ADC counts of X axis from accelerometer, where as -1 to 3 counts from Y axis . Why there is a much higher difference

Please answer ,Thank you.

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Eleon BORLINI
Eleon BORLINIBest answer
ST Employee
November 2, 2020

Hi @NMale.1​ ,

there are some reason for a non-zero g level at application level.

During the production, the device is calibrated in stand-alone condition, and the steady output is typically 0g (or 1g when along z axis).

But when you solder the device on a board, you have to consider that the soldering is almost never fully planar, so that you will have a residual tilt due to this fact.

As reported in the datasheet at p. 16:

Offset is to some extent a result of stress to MEMS sensor and therefore the offset can slightly change after mounting the sensor onto a printed circuit board or exposing it to extensive mechanical stress. Offset changes little over temperature, see Table 4 “Zero-g level change vs. temperature�? (TCOff). The zero-g level tolerance (TyOff) describes the standard deviation of the range of zero-g levels of a population of sensors

For this reason, a good practice is to measure the offset in the stationary position of the application board, store it in a software variable and the apply (sum or subtract)) the found value during the signal processing.

-Eleon

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Eleon BORLINI
Eleon BORLINIBest answer
ST Employee
November 2, 2020

Hi @NMale.1​ ,

there are some reason for a non-zero g level at application level.

During the production, the device is calibrated in stand-alone condition, and the steady output is typically 0g (or 1g when along z axis).

But when you solder the device on a board, you have to consider that the soldering is almost never fully planar, so that you will have a residual tilt due to this fact.

As reported in the datasheet at p. 16:

Offset is to some extent a result of stress to MEMS sensor and therefore the offset can slightly change after mounting the sensor onto a printed circuit board or exposing it to extensive mechanical stress. Offset changes little over temperature, see Table 4 “Zero-g level change vs. temperature�? (TCOff). The zero-g level tolerance (TyOff) describes the standard deviation of the range of zero-g levels of a population of sensors

For this reason, a good practice is to measure the offset in the stationary position of the application board, store it in a software variable and the apply (sum or subtract)) the found value during the signal processing.

-Eleon

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