25.3.2.2 TWI Host Operation

The TWI host is byte-oriented, with an optional interrupt after each byte. There are separate interrupt flags for the host write and read operation. Interrupt flags can also be used for polled operation. There are dedicated status flags for indicating ACK/NACK received, bus error, arbitration lost, clock hold, and bus state.

When an interrupt flag is set to ‘1’, the SCL is forced low. This will give the host time to respond or handle any data and will, in most cases, require software interaction. Clearing the interrupt flags releases the SCL. The number of interrupts generated is kept to a minimum by automatic handling of most conditions.