A communication system for an HDMI communication interface CEC channel includes a communication module for receiving messages via the CEC channel, a processing unit for processing the received messages and an oscillator for driving the communication module. When the interface is in an active mode, the system is operative to activate the timer upon detection of the start of transmission of a first message, detect the initial bit of the first message, reconstruct and process the first message, and switch the interface from the active mode to standby by deactivating the oscillator. When the interface is in standby, the system is operative to switch the interface to the active condition by activating the oscillator and the timer when the start of a transmission of a second message is detected, detect the initial bit of a transmission of the second message, and reconstruct and process the second message.