The use of CPOL/CPHA settings in SPI communication

Question

Could any one please give me real life examples where the 4 modes of CPOL/CPHA configuration in SPI communication are useful? I understand how they work but fail to know when to use them. I have read some refer shortly for compatibility purposes due to non-standard implementations, how is this so?

Thanks

Answer 1

SPI interface allows to transmit and receive data simultaneously on two lines (MOSI and MISO). Clock polarity (CPOL) and clock phase (CPHA) are the main parameters that define a clock format to be used by the SPI bus. Depending on CPOL parameter, SPI clock may be inverted or non-inverted. CPHA parameter is used to shift the sampling phase. If CPHA=0 the data are sampled on the leading (first) clock edge. If CPHA=1 the data are sampled on the trailing (second) clock edge, regardless of whether that clock edge is rising or falling.