Patent ID: 7930132

Claim:
An apparatus comprising: a first timer that indicates when a first period has lapsed by counting a clock signal having a predetermined frequency and that outputs a plurality of timing pulses, wherein each timing pulse is output each time the first period lapses; a second timer that indicates when a second period has lapsed by counting the timing pulses from the first timer; an accelerometer that measures an acceleration of a tire after each first period has lapsed; and a processor having a computer program embodied thereon, the computer program including: computer code for indicating that the tire is in rotation if at least one of the measured accelerations is greater than a first threshold; computer code for indicating that the tire is in rotation if an absolute difference between consecutive measured accelerations is greater than a second threshold; computer code for starting the second timer if the absolute difference is greater than the second threshold and if the second timer is not running; and computer code for indicating that the tire is rotating if the absolute difference is less than the second threshold and if the second timer is running.