An injection device, the injection device comprising: a housing containing a first electromechanical switch and a second electromechanical switch, each switch having an open state and a closed state and an associated actuator, wherein the actuators associated with each switch are arranged to contact a rotatable surface of the injection device at different relative circumferential positions； and a processor arrangement configured to: detect a change in the state of each of the switches； and determine a direction of rotation of the rotatable surface of the injection device from the detected state changes, wherein the rotatable surface is corrugated and wherein each switch has a first state when its respective actuator is located in a trough of a corrugation and a second state when its respective actuator is located on a crest of a corrugation.
