Abstract: An attitude- and motion-sensing system for an electronic device, such as a cellular telephone, a game device, and the like, is disclosed. The system, which can be integrated into the portable electronic device, includes a two- or three-axis accelerometer and a three-axis magnetic compass. Data about the attitude of the electronic device from the accelerometer and magnetic compass are first processed by a signal processing unit that calculates attitude angles (pitch, roll, and yaw) and rotational angular velocities. These data are then translated into input signals for a specific application program associated with the electronic device.