COMMUNICATION PROTOCOL BETWEEN A COMMUNICATION DEVICE AND AN EXTERNAL ACCESSORY

摘要

A method and apparatus for communicating both voice and control data between a communication device (such as a cellular phone) (100) and an external accessory (such as a hands-free kit) (102) over a data bus (101). The method includes formatting a sequence of bits into a repeating sequence of first time slots and second time slots, transmitting the voice data in the first time slot, and transmitting the control data in the second time slot. Notably, a first bit of each of the second time slots comprises a clock bit that alternates between a high value and a low value (e.g. a "1" or a "0") as between consecutive second time slots.