The present invention provides a drug injection device (100) comprising a first element (140) and a second element (103) configured to undergo unidirectional movement relative to each other corresponding to an action performed on or by the drug injection device (100), wherein the first element (140) comprises a plurality of serially disposed protrusions (143), wherein the second element (103) comprises first and second deflectable transducers (103a/153a, 103b/153b) configured for sequentially cooperating with the plurality of protrusions (143), and wherein a processor (151) is electrically connected with the first and second deflectable transducers (103a/153a, 103b/153b) to register activation signals, wherein the protrusion configuration is so disposed on the first element (140) and the first and second deflectable transducers (103a/153a, 103b/153b) are so disposed on the second element (103) that a second activation signal generated by the second deflectable transducer (103b/153b) is delayed relative to a first activation signal generated by the first deflectable transducer (103a/153a) as the first element (140) and the second element (103) move relative to each other, and wherein the processor (151) is configured to provide a) a first control action if a time delay between the first and second activation signals is above or equal to a pre-defined value, and b) a second control action if said time delay is below said pre-defined value.
