25.3.2.2.3 Transmitting Address Packets

The host starts performing a bus transaction when the Host Address (TWIn.MADDR) register is written with the client address and the R/W direction bit. The value of the MADDR register is then copied into the Host Data (TWIn.MDATA) register. If the bus state is Busy, the TWI host will wait until the bus state becomes Idle before issuing the Start condition. The TWI will issue a Start condition, and the shift register performs a byte transmit operation on the bus.

Depending on the arbitration and the R/W direction bit, one of four cases (M1 to M4) arises after the transmission of the address packet.