1 What is Auto Increment?

In I2C auto increment refers to the register address automatically increasing to the next byte (such as from register 1 to register 2) when a consecutive byte is read or written without performing a stop condition.

Traditionally in I2C, to write data to a register the user needs to send the I2C target address followed by the register number then the data required to be written into the register. Figure 1-1 shows a generic example of an I2C single write transaction. If the user needed to write to additional registers in the I2C device, additional write transactions are required. This process looks similar to Figure 1-1 with multiple transactions instead of just one.

Figure 1-1 I2C Single Write

For read transactions, the I2C transactions are more involved since reads require a prior write to set the pointer or address of the read register. Figure 1-2 shows a generic example of a single read transaction which begins with a write to set the required register to read from first.

Figure 1-2 I2C Single Read