8.3.1.2.1 Time Division Multiplexed Audio (TDM) Interface

In TDM mode, also known as DSP mode, the rising edge of FSYNC starts the data transfer with the slot 0 data first. Immediately after the slot 0 data transmission, the remaining slot data are transmitted in order. FSYNC and each data bit (except the MSB of slot 0 when TX_OFFSET equals 0) is transmitted on the rising edge of BCLK. Figure 24 to Figure 27 illustrate the protocol timing for TDM operation with various configurations.

Figure 24. TDM Mode Standard Protocol Timing (TX_OFFSET = 0)

Figure 25. TDM Mode Protocol Timing (TX_OFFSET = 2)

Figure 26. TDM Mode Protocol Timing (No Idle BCLK Cycles, TX_OFFSET = 2)

Figure 27. TDM Mode Protocol Timing (TX_OFFSET = 0 and BCLK_POL = 1)

For proper operation of the audio bus in TDM mode, the number of bit clocks per frame must be greater than or equal to the number of active output channels times the programmed word length of the output channel data. The device supports FSYNC as a pulse with a 1-cycle-wide bit clock, but also supports multiples as well. For a higher BCLK frequency operation, using TDM mode with a TX_OFFSET value higher than 0 is recommended.