A key control device and a key control method are disclosed. The key control device includes: an encoder circuit including a first output terminal and a second output terminal and configured to output a first voltage signal and a second voltage signal through the first output terminal and the second output terminal respectively, under triggering of a rotational operation; a first interface extension circuit configured to receive the first voltage signal and the second voltage signal, and generate an interrupt signal and voltage state transition data in response to the first voltage signal or the second voltage signal output by the encoder circuit; and a main control circuit configured to determine a rotation direction of the rotation operation according to the interrupt signal and the voltage state transition data.

Motion detection device consisting of a single encoder and a single stationary sensor element, the encoder, which is arranged on a movable part, representing an asymmetrical pattern. The angular velocity or velocity and the direction of motion of a moving part are determined from the sensor signal by measuring the edge steepness or the rise time or fall time, spectrally analyzing the frequency and the phase relation of a harmonic to the phase of the fundamental mode, or evaluating the asymmetries of a sequence of rectangular pulses.