Patent ID: 7742438

Claim:
A method for transmitting control data between a high-bandwidth digital content protection (HDCP) transmitting device and an HDCP receiving device via a transmitter and a receiver configured to communicate with each other over a single, duplex communication channel, the method comprising: the transmitter receiving from the HDCP transmitting device a read transaction request for HDCP control data via a first serial bus including at least a first signal line dedicated for transmitting a clock signal and a second signal line for transmitting the HDCP control data; responsive to the transmitter not having received the requested HDCP control data, the transmitter sending a negative acknowledgement signal to the HDCP transmitting device via the first serial bus; the transmitter receiving the requested HDCP control data from the HDCP receiving device via the receiver, the receiver receiving the requested HDCP control data from the HDCP receiving device via a second serial bus including at least a third signal line dedicated for transmitting the clock signal and a fourth signal line for transmitting the HDCP control data, and the transmitter receiving the requested HDCP control data from the receiver without the clock signal over the single, duplex communication channel, wherein the single, duplex communication channel does not have a dedicated clock signal line and is not capable of carrying the clock signal and the HDCP control data at the same time; the transmitter receiving from the HDCP transmitting device a retry read request for the HDCP control data via the first serial bus; and the transmitter providing the HDCP control data to the HDCP transmitting device via the first serial bus.