As shown in Figure 9-10, a single-byte data-write transfer begins with the primary device transmitting a start condition followed by the I²C device address and the R/W bit. The R/W bit determines the direction of the data transfer. For a write data transfer, the R/W bit is a 0. After receiving the correct I²C device address and the R/W bit, the device responds with an acknowledge bit. Next, the primary transmits the address byte or bytes corresponding to the internal memory address being accessed. After receiving the address byte, the device again responds with an acknowledge bit. Next, the primary device transmits the data byte to be written to the memory address being accessed. After receiving the data byte, the device again responds with an acknowledge bit. Finally, the primary device transmits a stop condition to complete the single-byte data-write transfer.

Figure 9-10 Random Write Transfer