I2C

The I2C bus was designed by Philips in the early ’80s to allow easy communication between components which reside on the same circuit board. Philips Semiconductors migrated to NXP in 2006.

The name I2C translates into “Inter IC”. Sometimes the bus is called IIC or I²C bus. There are two wires, SDA and SCL.

The first thing to realize: SDA and SCL are open-drain (also known as open-collector in the TTL world), that is I2C master and slave devices can only drive these lines low or leave them open

It has a 7 bit addressing scheme (along with a rarely used 10 bit scheme). Transmissions are done in 8 byte bursts, which the first byte of the transmissing being an address and a 1 bit read or write flag.

Overview of Microchip's MSSP module link.