Aspects of the disclosure provide an audio circuit that includes a clock circuit, a transmitting circuit, an audio data preparation circuit and a controller. The controller is configured to provide control signals to configure the transmitting circuit and the audio data preparation circuit according to one of a plurality of link protocol. The clock circuit is configured to provide a clock signal for bit transmission. The transmitting circuit is configured to transmit a bit in response to a transition edge of the clock signal according to the link protocol. The audio data preparation circuit is configured to insert audio data into a bit stream and provide the bit stream to the transmitting circuit according to the link protocol.