Electrical power transmitting controller device and electrical power receiving controller device for using in a communication system

A host device (10) may comprise an electrical power transmitting controller device (100), and an accessory device (20) may comprise an electrical power receiving controller device (200). After an identification and handshaking process to determine power requirements the power transmitting controller device (100) provides electrical power to the electrical power receiving controller device (200) to operate the accessory device. Coded communication data is transferred between the host device (10) and the accessory device (20) by a communication link. Power and communication are transferred over a single wire, such as an auxiliary pole (AUX) of a 3.5 mm jack interface (1020).