24.4.3.3.1 Single Data Rate (SDR) Mode

SDR mode is the default mode of the I³C bus. SDR mode is also used to enter other modes, sub-modes, states, and for built-in features such as Common Commands (CCCs), in-band interrupts, and transition from I²C to I³C by assignment of a Dynamic Address.

I³C SDR mode is significantly similar to the I²C protocol in terms of procedures and conditions, and as a result, I³C devices and many Legacy I²C Target devices (but not Legacy I²C Controller devices) can coexist on the same I³C bus. However, SDR mode also includes numerous new features that are not present in I²C. For the procedures and conditions that I³C shares with I²C, SDR mode closely follows the definitions in the I²C Specification. I²C traffic from an I³C Controller to an I²C Target will be properly ignored by all I³C Targets because the I³C protocol is designed to allow I²C traffic. I³C traffic from an I³C Controller to an I³C Target will not be seen by most Legacy I²C Target devices because the I²C Spike Filter is opaque to I³C’s higher clock speed.