2.1.8 Acknowledge Sequence

The ninth SCL pulse for any transferred byte in I²C is dedicated as an Acknowledge sequence (ACK). It allows receiving devices to respond back to the transmitter by pulling the SDA line low. The transmitter must release control of the line during this time to shift in the response. The Acknowledge (ACK) is an active-low signal. Pulling the SDA line low indicates to the transmitter that the device has received the transmitted data and is ready to receive more.

The result of an ACK is placed in the Acknowledge Status (ACKSTAT) bit.

The master software allows the user to select the ACK value sent back to the transmitter. The Acknowledge Data (ACKDT) bit is set/cleared to determine the response.