7.6.6.7.1 Channel Index Mode
Channel Index mode sends the index of the channel on the MSB of the PDMC_RHR register (bits 31 to 24).
This mode is accessed by setting PDMC_CFGR.PACK to 0 and PDMC_MR.RHRMSB to 0. The value of PDMC_MR.RHRJUSTIF has no effect.
The length of the audio word is defined by PDMC_CFGR.DATAL, and data are located on the LSB of PDMC_RHR.