The ADAR7251's spi timing required is as following figure, the first 3 bytes a command sent by TMS320F28335, after AD receive the command, it send 2 bytes data to TI 28335,
I set SPIA FIFO level to 5 bytes(the first 3 bytes are command, the last 2 bytes are dummy write)
firstly , I sent 5 byte to disable CRC
0x00 0xFD,0x00, 0x00,0x01, 0x33,0x06
cuz when POR, ADAR7251's CRS is enabled, the 0x33, 0x06 is CRC comand, ADDR15 is set to 0 voltage
I check the sent 5-bytes from TI 28335 on the oscilloscope(view line SPI MOSI), it is right. but no bits appears on the line SOMI, would someone help me? it puzzled me a few days