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Visitor II
October 31, 2020
Solved

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

  • October 31, 2020
  • 1 reply
  • 1019 views

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.

    This topic has been closed for replies.
    Best answer by Eleon BORLINI

    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

    1 reply

    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