of FPD-Link. National Semiconductor designed it specifically for automotive infotainment and camera interface applications. FPD-Link II embeds the clock in the data signal and therefore uses only one differential pair to transmit both the clock and video data. This further reduces the size, weight, and cost of cables for infotainment and safety camera applications. For example, the 24-bit color application now uses only one twisted pair instead of the 5 twisted pairs used by FPD-Link. There are additional benefits from FPD-Link II. For example, the car makers appreciate the increased cable length even with reduced cable cost. This is because of the embedded clock feature that eliminates the timing skew between clock and data signals. This was the limiting factor to cables with separate clock and data pairs because all pairs had to be manufactured at precisely equal length to control the timing skew between the clock and data pairs. This length matching added to the cable cost. Another benefit for FPD-Link II comes from adding DC balance to the signals. Because the signal is DC balanced the application can use AC coupling, which eliminates the ground current problem between data source and destination. This is critical in the automotive applications because of the potential for large transient currents that can damage sensitive electronic equipment. FPD-Link III FPD-Link III was introduced in 2010. Further improving FPD-Link II, FPD-Link III's major feature is embedding a bidirectional communication channel on the same differential pair. This bidirectional channel transfers control signals between source and destination in addition to the clock and streaming video data. Therefore, FPD-Link III even further reduces cable cost by eliminating cables for control channels such as I2C and CAN bus. FPD-Link III's embedded control channel uses the I2C bus protocol between the source and destination in the first implementations (however, it is not limited to I2C). The I2C master can read and write to all the slaves on the other side of the FPD-Link III chipset, which is effectively transparent to the I2C master and slaves communications. For example, this enables infotainment head units to control and configure displays, and image processing units to control and configure cameras using the same twisted pair cable as the data transmission. The Digital Content Protection LLC approved FPD-Link III in 2009 as a high-bandwidth interface for carrying content whose owner wants HDCP security. This approval enables the FPD-Link III chipsets to include