Digital audio data flows between the host processor and the PCM1822 on the digital audio serial interface (ASI), or audio bus. This highly flexible ASI bus includes a TDM mode for multichannel operation, support for the I²S, and the pin-selectable master-slave configurability for bus clock lines.

The device supports an audio bus master or slave mode of operation using the hardware pin MSZ. In slave mode, FSYNC and BCLK work as input pins whereas in master mode, FSYNC and BCLK work as output pins generated by the device. Table 8-1 shows the master and slave mode selection using the MSZ pin.

The bus protocol TDM or I²S format can be selected by using the FMT0 pin. As shown in Table 8-2, these modes are all most significant byte (MSB)-first, pulse code modulation (PCM) data format, with an output channel data word-length of 32 bits.