The SDI input-data word is 16 bits long and consists of the following format:
The SDO output-data word is 16 bits long and the first 8 bits are don’t care bits. The data word is the content of the register being accessed.
For a write command (W0 = 0), the response word on the SDO pin is the data currently in the register being written to.
For a read command (W0 = 1), the response word is the data currently in the register being read.
The SCLK pin should be low at power-up of the device for reliable SPI transaction. If the SCLK pin cannot be guaranteed to be low at power-up, TI recommends performing a dummy SPI-read transaction (of any register) after power-up to ensure reliable subsequent transactions. Data read from this dummy read transaction should be discarded.