I²C (2-wire), is a multi-master, multi-slave, packet switched, single-ended, serial computer bus invented in 1982 by Philips Semiconductor (now NXP Semiconductors). I2C is a serial communication protocol, so data is transferred bit by bit along a single wire (the SDA line). It is widely used for attaching lower-speed peripheral ICs to processors and microcontrollers in short-distance, intra-board communication. I2C is synchronous, so the output of bits is synchronized to the sampling of bits by a clock signal shared between the master and the slave. The clock signal is always controlled by the master.
I2C data is transferred in messages. Messages are broken up into frames of data. Each message has an address frame that contains the binary address of the slave, and one or more data frames that contain the data being transmitted. The message also includes start and stop conditions, read/write bits, and ACK/NACK bits between each data frame
Alternatively I²C is spelled I2C (pronounced I-square-C) or IIC (pronounced I-I-C).
List of known I²C memory cards:
- Atmel (now Microchip): AT24C01A, AT24C02, AT24C04, AT24C08, AT24C1024, AT24C128, AT24C16, AT24C164, AT24C256, AT24C32, AT24C512, AT24C64, AT24CS128, AT24CS256
- Microchip: 24LC01SC, 24LC02SC, 24LC04SC, 24LC08SC, 24LC16SC, 24LC32SC, 24LC64SC, 24LC128SC, 24LC256SC, 24LC512SC, 24LC1024SC
- Gemalto (GemPlus):