I2C

IC (Inter-Integrated Circuit; pronounced as "" or ""), alternatively known as I2C and IIC, is a synchronous, multi-master/multi-slave, single-ended, serial communicationbus invented in 1980 by Philips Semiconductors (now NXP Semiconductors). It is widely used for attaching lower-speed peripheral integrated circuits (ICs) to processors and microcontrollers in short-distance, intra-board communication.

The IC bus can be found in a wide range of electronics applications where simplicity and low manufacturing cost are more important than speed. PC components and systems which involve IC include serial presence detect (SPD) EEPROMs on dual in-line memory modules (DIMMs) and Extended Display Identification Data (EDID) for monitors via VGA, DVI, and HDMI connectors. Common IC applications include reading hardware monitors, sensors, real-time clocks, controlling actuators, accessing low-speed DACs and ADCs, controlling simple LCD or OLED displays, changing computer display settings (e.g., backlight, contrast, hue, color balance) via Display Data Channel, and changing speaker volume.

A particular strength of IC is the capability of a microcontroller to control a network of device chips with just two general-purpose I/O pins. Many other bus technologies used in similar applications, such as Serial Peripheral Interface Bus (SPI), require more pins and signals to connect multiple devices.

System Management Bus (SMBus), defined by Intel and Duracell in 1994, is a subset of IC, defining a stricter usage. One purpose of SMBus is to promote robustness and interoperability. Accordingly, modern IC systems incorporate some policies and rules from SMBus, sometimes supporting both IC and SMBus, requiring only minimal reconfiguration either by commanding or output pin use. System management for PC systems uses SMBus, whose pins are allocated in both conventional PCI and PCI Express connectors.