This parameter can be one of the following values: SPI_CRC_LENGTH_DATASIZE: aligned with the data size SPI_CRC_LENGTH_8BIT : CRC 8bit SPI_CRC_LENGTH_16BIT : CRC 16bit.
This parameter can be one of the following values: SPI_RXFIFO_THRESHOLD or SPI_RXFIFO_THRESHOLD_QF : RXNE event is generated if the FIFO level is greater or equal to 1/4(8-bits). SPI_RXFIFO_THRESHOLD_HF: RXNE event is generated if the FIFO level is greater or equal to 1/2(16 bits).