SDAA014 November   2025 AM2752-Q1 , AM2754-Q1

 

  1.   1
  2.   Abstract
  3.   How to Use this Document
  4.   Trademarks
  5. 1Digital Audio Formats
    1. 1.1 I2S
    2. 1.2 TDM
  6. 2McASP Overview
  7. 3McASP Connections for AM275x
    1. 3.1 McASP Common Configurations
      1. 3.1.1 McASP as a Clock Controller
        1. 3.1.1.1 Clocks Generated using the Internal Audio PLL
        2. 3.1.1.2 Clocks Generated using the AUDIO_EXT_REFCLK AUXCLK Source
        3. 3.1.1.3 Clocks Generated using the AUDIO_EXT_REFCLK AHCLK Source
      2. 3.1.2 McASP as Clock Peripheral
        1. 3.1.2.1 Clock Externally Generated with AUDIO_EXT_REFCLK Input
  8. 4McASP Layout Considerations
    1. 4.1 McASP Signals Shared with Bootmode Logic
    2. 4.2 McASP Topology for Multiple Devices in Single Clock Domain
  9. 5ASRC Overview
  10. 6McASP Practical Examples
    1. 6.1 Audio Playback with Internal Audio PLL for Two Clock Domains
    2. 6.2 Audio Playback with External Clock Source and McASP SYNC mode
    3. 6.3 Audio Playback with ASRC Bridging Two Clock Domains
  11. 7Key Audio System Design Takeaways
  12. 8References

1.2 TDM

Time Division Multiplexing (TDM) is a standard digital audio protocol for multichannel audio transmission. Typically, TDM is followed by a number that indicates the channel count per audio frame such as TDM4. TDM does not have a standardized format, but a typical TDM frame is defined by the following characteristics:

  • Rising edge of frame sync indicates frame start
  • 1-bit clock cycle delay between frame sync rising edge and data transmission
  • Single bit frame sync width
  • Most significant bit first serial bitstream order
  • Data shifted out on falling edge of bit clock
  • Data sampled in on rising edge of bit clock

TDM4 Timing Diagram Figure 1-3 TDM4 Timing Diagram