26.3.4.3 TWI Slave Operation

The TWI slave is byte-oriented with optional interrupts after each byte. There are separate slave data and address/stop interrupt flags. Interrupt flags can also be used for polled operation. There are dedicated status flags for indicating ACK/NACK received, clock hold, collision, bus error, and read/write direction.

When an interrupt flag is set, the SCL line is forced low. This will give the slave time to respond or handle data, and will in most cases require software interaction. Figure 26-16. shows the TWI slave operation. The diamond shapes symbols (SW) indicate where software interaction is required.

Figure 26-16. TWI Slave Operation

The number of interrupts generated is kept to a minimum by automatic handling of most conditions. Quick command can be enabled to auto-trigger operations and reduce software complexity.

Address Recognition Mode can be enabled to allow the slave to respond to all received addresses.