A rotary element is equipped with a pattern representing a reflected binary code on at least three bits. A detection circuit is configured to sense the pattern and deliver an incident signal encoded in reflected binary code on at least three bits. The incident signal is converted by a transcoding circuit into an intermediate signal encoded in reflected binary code on two bits. A decoding stage decodes the intermediate signal and outputs at least one clock signal representing the amount of rotation of the rotary element and a direction signal representing the direction of rotation. A processing circuit determines the movement of the rotary element, and has at least one general purpose timer designed to receive the at least one clock signal and direction signal.