Hello @FedIng
The embedded self-test functions allow checking the device functionality without moving it.
Also, When the accelerometer self-test is enabled, an actuation force is applied to the sensor, simulating a definite input acceleration. In this case, the sensor outputs exhibit a change in their DC levels which are related to the selected full scale through the sensitivity value.
The accelerometer self-test function is off when the ST[1:0]_XL bits of the CTRL5_C register are programmed to 00. It is enabled when the ST[1:0]_XL bits are set to 01 (positive sign self-test) or 10 (negative sign self-test). When the accelerometer self-test is activated, the sensor output level is given by the algebraic sum of the signals produced by the acceleration acting on the sensor and by the electrostatic test-force.
For more informations about the self-test, take a look at the chapter 9 of the AN5296.
Best regards.
II