47.5.13.2 I8S (I2S) - 32-BIT FLOATING POINT AUDMOD = 00, AUDFMT[2:0] = 110, AUDWD_MODE[1:0] = 01
For I8S standard mode, AM other format mode 32-bit Floating Point format, the configuration bits in SPIxCTRL_* must be set as follows: AUDMOD=00, AUDEN=1, FRMPOL=0, CPOL=1, CPHA = 1, FRMSYPW=0100, FRMCNT=011, AUDFMT[2:0]=110, AUDWD_MODE[1:0]=01, FRMCOINC=0. These values set SDO and LRC transitions to occur on the falling edge of SCK and sampling of SDI to occur on the rising edge of SCK. The following figure shows the format of the 32-bit word to store in memory.
I2S is supported as part of the legacy mode of operation and is not described here.