As shown in Table 4, the host controller can use any of the four legacy, SPI-compatible protocols (SPI-00-S, SPI-01-S, SPI-10-S, or SPI-11-S) to write data to the device.
|PROTOCOL||SCLK POLARITY |
(At CS Falling Edge)
|SCLK PHASE |
|SDI_CNTL||SDO_CNTL||NO. OF SCLK|
(Optimal Command Frame)
At power-up or after coming out of any asynchronous reset, the device supports the SPI-00-S protocol for data-read and data-write operations.
To select a different SPI-compatible protocol, program the SDI_MODE[1:0] bits in the SDI_CNTL register. This first write operation must adhere to the SPI-00-S protocol. Any subsequent data transfer frames must adhere to the newly selected protocol.
As explained in the Data Transfer Frame section, a valid write operation to the device requires a minimum of 22 SCLKs to be provided within a data transfer frame.
Any data write operation to the device must continue to follow the SPI-compatible protocol selected in the SDI_CNTL register, irrespective of the protocol selected for the data-read operation.