Patent ID: 8650930

Claim:
A method for failsafe self checking a motion sensor module comprising the steps of: (a) providing a motion sensor module having an output signal port and a test activation port, the motion sensor module being responsive to an application of a first test voltage to the test activation port to initiate a sequence of self tests within the sensor module, the self tests providing a test response signal on the output signal port, the first test voltage having a first predetermined duration to allow completion of the sequence of self tests after which the test activation port voltage reverts to its original value, the motion sensor module also having a test status port that changes voltage in response to the first test voltage being applied to the test activation port, the state of the test status port voltage also reverting to its original value in response to the test activation port voltage reverting to its original value; (b) applying a second test voltage to the test activation port, the second test voltage having a second predetermined duration that is less than the first predetermined duration of the first test voltage; (c) monitoring the test status port for a voltage in response to the second test voltage being applied to the test activation port; and (d) generating an error signal if the test status port voltage does not change in response to the second test voltage being applied to the test activation port.