Start, Stop and Restart Conditions

All transactions on the I3C bus begin with a Start condition asserted by the Controller. A Start condition is a high-to-low transition on the SDA line while the SCL is at a constant high. The Target sets the SCIF interrupt flag when it detects a Start condition on the bus.
All transactions on the I3C bus end with a Stop condition asserted by the Controller. A Stop condition is a low-to-high transition on the SDA line while the SCL is at a constant high. The Target sets the PCIF interrupt flag when it detects a Stop condition on the bus.
As an alternative to the Stop condition, a Restart condition allows multiple messages to be sent while in the same frame without needing to transmit a Stop and Start in between messages. A Restart condition looks the same as a Start condition on the bus. The Target sets the RSCIF interrupt flag when it detects a Restart condition on the bus.

The Start, Restart and Stop conditions in I3C protocol are identical to the ones in I2C protocol. Figure 1 below shows the Start, Restart and Stop conditions on the bus.

Figure 1. Start, Restart and Stop Conditions