The Book of I2C

5 I²C Variants

This chapter briefly describes several variants of the I²C bus, including the System Management Bus (SMBus), VESA DDC and E-DDC, ACCESS.bus, and two-wire interface. For the most part, these variants apply a protocol on top of the physical two-wire interface of the I²C bus, defining messages and other data flowing across the bus.

Going into detail on such protocol extensions is generally beyond the scope of this book. Nevertheless, this chapter gives an overview of those protocols (and information for other specific bus variants) and explains where you can find more information about these variants. We begin with the SMBus ...