Posted on March 19, 2015 at 19:32From the datasheet:
Self-test allows to check the sensor functionality without moving it. The self-test function isoff when the self-test bit (ST) is programmed to ‘0‘. When the self-test bit is programmed to‘1‘ an actuation force is applied to the sensor, simulating a definite input acceleration. In thiscase the sensor outputs exhibit a change in their DC levels which are related to the selectedfull scale through the device sensitivity. When self-test is activated, the device output level isgiven by the algebraic sum of the signals produced by the acceleration acting on the sensorand by the electrostatic test-force. If the output signals change within the amplitudespecified inside Table 3, then the sensor is working properly and the parameters of theinterface chip are within the defined specifications.
When you activate the Self Test it will apply a force to the MEMS to change the acceleration value that you read, without actually moving the device. We use it in production test when the object is in a stable location. Read the XYZ. Apply self Test. Read XYZ again. The values should change between the reading with test enabled vs disabled.
