Inter-Integrated Circuit (I2C)

I2C, pronounced I-squared-C, is a serial bus that provides communication between sensors and microcontrollers such as the Arduino. In contrast to the full-duplex SPI specification, I2C has a slower data rate, and data can only travel in one direction at a time. Arduino uses 7-bit values to reference I2C addresses, and devices using I2C must use a common ground to communicate.