The name I²C is short hand for a standard Inter-IC (integrated circuit) bus. I²C is a simple protocol with low-bandwidth and short-distance for data transfer. Most I²C devices operate at speeds up to 400Kbps. The I²C is easy to use for linking multiple devices together since it has a built-in addressing scheme. The I²C bus is a two wire serial bidirectional interface consisting of SCL (clock) and SDA (data). Both the wires are connected to the device supply via pull-up resistors. The I²C protocol defines any device that sends data onto the bus as a transmitter and the receiving device as the receiver. The device controlling the transfer is a master and the device being controlled is the slave. The transmitting device pulls down the SDA line to transmit a “0” and releases it to transmit a “1”. The master always initiates the data transfer, only when the bus is not busy, and provides the clock for both transmit and receive operations. The serial communication over the I²C interface is conducted by sending the most significant bit (MSB) of each byte of data first.