27.3.2.2.3.3 Case M3: Address Packet Transmit Complete - Address not Acknowledged by Slave
If no slave device responds to the address
packet, the WIF and the RXACK flags will be set to ‘1’. The clock hold is
active at this point, forcing the SCL low.
The missing ACK response can indicate that the I2C slave is busy with other tasks, or it is in a Sleep mode, and it is not able to respond.
The software can prepare to take one of the
following actions:
- Retransmit the address packet
- Complete the transaction by issuing a Stop condition in the Command (MCMD) bit field from the Master Control B (TWIn.MCTRLB) register, which is the recommended action