19.4.2.6.2 Host Mode Clocking and MCLK

The SPI module as a host has the ability to generate BCLK and LRCK by internally generating using SPICLK (MCLKEN = 0). In addition, the 33A device can generate the clock for external codec devices using the reference output, REFCLKO function (see Reference Clock Output (REFOx)), although some codecs may have the ability to generate their own MCLK from a crystal to provide accurate audio sample rates.

Figure 19-30 shows that the REFCLKO clock can be used as MCLKIN by the codec.

Figure 19-29. SPIx Host Clock Generation

Figure 19-30 shows the interface between an SPI client and a codec host, deriving the clock from the MCLK input interface.

Figure 19-30. SPIx Client and Codec Host – Clock Derived from MCLK