Testing AD7686, using a three wire no busy mode, collecting SCK&SDO with an oscilloscope, it was found that SDO is not controlled by SCK; Put it another way, the clock frequencies of SCK and SDO are the same. Is it because the AD7686 module is faulty
Here are the parameters for initializing SPI:
SPI_InitStructure.SPI_Direction = SPI_Direction_2Lines_RxOnly;
SPI_InitStructure.SPI_Mode = SPI_Mode_Master;
SPI_InitStructure.SPI_DataSize = SPI_DataSize_8b;
SPI_InitStructure.SPI_CPOL = SPI_CPOL_Low;//SPI_CPOL_High;
SPI_InitStructure.SPI_CPHA = SPI_CPHA_2Edge;
SPI_InitStructure.SPI_NSS = SPI_NSS_Soft;
SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_256;
SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;
SPI_InitStructure.SPI_CRCPolynomial = 7;
SPI_Init(SPI1, &SPI_InitStructure);
