Three-level motion detector using accelerometer device in key fob application

A remote access device, comprising:

• a wireless transmitter configured to operate in a first operating mode and in a second operating mode;
• and
• an accelerometer configured to:
• detect a first change in motion states of the remote access device between a first motion state and a second motion state,
• detect a second change in motion states of the remote access device between the second motion state and a third motion state,
• detect a third change in motion states of the remote access device between the first motion state and the third motion state, and
• generate, in response to detecting any of the first change in motion states, the second change in motion states, and the third change in motion states, a hardware interrupt that causes the wireless transmitter to transition from the first operating mode to the second operating mode.

A method, comprising:

• causing a wireless transmitter to operate in a first mode at a first time;
• detecting a first change in motion states based on a first set of measurements by the accelerometer at a second time subsequent to the first time;
• causing the wireless transmitter to transition to a second mode for a defined period in response to detecting the first change in motion states;
• detecting a second change in motion states based on a second set of measurements by the accelerometer at a third time subsequent to the first time;
• causing the wireless transmitter to transition to the second mode for the defined period in response to detecting the second change in motion states;
• detecting a third change in motion states based on a third set of measurements by the accelerometer at a fourth time subsequent to the first time;
• and
• causing the wireless transmitter to transition to the second mode for the defined period in response to detecting the third change in motion states.