When the APB - I2C IP is programmed as the I2C slave interface, the APB controller polls the status
register to know whether a read or write is happening in the I2C interface. When a read or write is
completed the APB controller takes away the data from the FIFO by reading the data length registers and
address registers to map the register locations. This block throttles the data flow between the I2C interface
and the APB controller in slave mode