An accessory for a portable electronic device, such as a digital music player, includes a set of device controls for controlling the portable electronic device. The accessory includes a microprocessor and a memory that contains function codes corresponding to the functions selected by the controls. Preferably, the accessory is a charger is adapted to be inserted into for a 12-volt car auxiliary power outlet and the protruding face of the charger body is a click wheel controller that rotates. The accessory may also include a FM transmitter for transmitting an audio signal received from the portable electronic device to the car stereo and a verification system for insuring the charger is produced by an authorized supplier.