First, the master will issue a START condition. This acts as an ‘Attention’ signal to all of the connected devices. All ICs on the bus will listen to the bus for incoming data.
Then the master sends the ADDRESS of the device it wants to access, along with an indication whether the access is a Read or Write operation (Write in our example). Having received the address, all IC’s will compare it with their own address. If it doesn’t match, they simply wait until the bus is released by the stop condition (see below). If the address matches, however, the chip will produce a response called the ACKNOWLEDGE signal.