Audio/video communication system and method

Abstract

A communication system for e.g. an automobile including a system control unit for activating a selected audio/video device (such as an AM/FM tuner or a navigation system) in response to a request signal transmitted on a bus from a command input terminal. The system control unit generates command signals necessary to activate the selected audio/video device in response to the request signal, including command signals to de-activate any currently-operating devices. Conversely, adjustment commands (such as volume change or channel change commands) are transmitted directly (that is, unchanged by the system control unit) from the command input terminal to the selected audio/video device on the first bus line. In addition, the audio/video devices transmit reset signals whenever power is shut-off and then restored. Each reset signal includes a transmission source address corresponding to the audio/video device which transmitted the signal. The system control unit compares these transmission source addresses with a stored address corresponding to the selected audio/video device, and transmits a command signal to restart the selected audio/video device. Further, when the system control unit is turned off and then restored, the system control unit transmits a reset command to all of the audio/video devices connected to the bus.