I²C Concepts

The I²C bus is available on several ARM, 8051, 251, and 166/ST10 devices and may be implemented in several different ways.

I²C serial port with hardware implemented Master and Slave functions (as in NXP (formerly Philips) 80C552, 558, and several Atmel devices).
Combined SPI/I²C interface with hardware implemented Slave and Software based Master functions (as in Analog Devices ADuC812, ADuC824 and several other devices).
Single bit hardware for software based Master and Slave support (as in NXP 8xC75x and NXP LPC series, described in NXP AN422 available from the NXP Web page).
Using the High-Speed Serial Interface of the Infineon 166/ST10 family for simulation of the I²C bus. (Described in the Infineon AppNote AP1626).
Software based simulation of a I²C Bus Master device. This can be implemented in any 8051 or 166 device be using two un-used I/O pins as SCL and SDA pins. These I/O pins are controlled by software only.

The following information about I²C Simulation applies to devices with an I²C interface hardware.