Programming AVR I2C interface. I2C (also referred as IIC or TWI) is widely used interface in embedded applications.
Two wire bus initially was used by Philips and become a standard among chip vendors. I2C bus consists of two lines called Serial Data Line (SDA) and Serial Clock Line (SCL). Communication is relatively fast and short distance mainly used to communicate between sensors, RTC, EEPROM, LCD. Optical Encoder Wheel Generator. Arduino Programming Reference.