The present invention relates to electronically assisted drug delivery devices (100). The drug delivery device may include a Gray code type detector for sensing dosage data, wherein the detector comprises a code track consisting of a sequence of alternating markings and a plurality of detectors that are mutually spaced in a direction extending along the code track. The drug delivery device may also include a dosage selector (260) which is moved in a proximal direction upon dose setting and in a distal direction upon dose injection, where the dosage selector is latched in the end of dose position by a latching element, the latching element actuating an end of dose switch for signalling the end of dose state. The drug delivery device may also incorporate power-management arrangements which effectively minimizes power consumption for the incorporated electronic circuitry.