To communicate with the OPT3004, the controller must first initiate an I²C start command. Then, the controller must address target devices via a target address byte. The target address byte consists of seven address bits and a direction bit that indicates whether the action is to be a read or write operation.

Four I²C addresses are possible by connecting the ADDR pin to one of four pins: GND, VDD, SDA, or SCL. Table 8-1 summarizes the possible addresses with the corresponding ADDR pin configuration. The state of the ADDR pin is sampled on every bus communication and must be driven or connected to the desired level before any activity on the interface occurs.