1 I²C Specification

The I²C Specification was developed by Philips Semiconductors to communicate between devices connected to a two-wire bus. Philips recognized that there were many similarities between consumer electronics, industrial electronics and telecommunications designs. These designs often contained similar components, such as Analog-to-Digital Converters (ADCs), Liquid Crystal Displays (LCDs) or external memory modules. Philips determined that they could simplify system design and maximize hardware efficiency by creating a communications scheme that could be used to transfer data between any device connected to a common bus. The I²C Specification allowed system designers to use devices from multiple manufacturers, or use one device in several applications. The Specification also solved interfacing issues by creating a standard protocol that is now held as an industry standard, meaning any I²C device can communicate with any other I²C device changing the hardware or firmware of either device.

The I²C Specification defines the bus as a two-wire, bidirectional communications network. One line carries the Serial Data (SDA) signal, and the other line carries the Serial Clock (SCL) signal. Each I²C device connected to a bus has a unique address, either 7 bits or 10 bits in length. An I²C device may operate as a bus master, a bus slave, or both, depending on the device and the application in which the device is used.