SBAU398 March   2022

 

  1.   Trademarks
  2. 1Introduction
  3. 2Hardware Overview
    1. 2.1 AC-MB Settings
      1. 2.1.1 Audio Serial Interface Settings
        1. 2.1.1.1 USB
        2. 2.1.1.2 Optical or Auxilary Analog Audio Input
        3. 2.1.1.3 External
      2. 2.1.2 AC-MB Power Supply
    2. 2.2 ADCx120Q1EVM-PDK Hardware Settings
      1. 2.2.1 Line Inputs
      2. 2.2.2 Onboard Microphone Configuration
      3. 2.2.3 External Microphone Configurations
  4. 3Software Overview
    1. 3.1 PurePath Console 3 Installation
    2. 3.2 ADCx120Q1EVM GUI Installation
      1. 3.2.1 Software Setup
  5. 4GPIO1 Settings
  6. 5Master Mode Operation
  7. 6Quick Start
    1. 6.1 Configuring the Audio Serial Bus for the I2S Output
    2. 6.2 Saving a Configuration
  8. 7Schematic and Bill of Materials
    1. 7.1 ADCx120Q1EVM-PDK Schematic and Bill of Materials
      1. 7.1.1 ADCx120Q1EVM-PDK Schematic
      2. 7.1.2 ADCx120Q1EVM-PDK Bill of Materials
    2. 7.2 AC-MB Schematic and Bill of Materials
      1. 7.2.1 AC-MB Schematic
      2. 7.2.2 AC-MB Bill of Materials
    3. 7.3 Matlab Audio Capture Example

6.1 Configuring the Audio Serial Bus for the I2S Output

The PCMx120-Q1 features a highly flexible audio serial bus that can be configured to implement a wide range of data formats. The default format is TDM, however the GUI can be used to change the data format to I2S. This section describes how to configure the PCMx120-Q1 EVM for a 2-channel I2S output to a USB audio at 16 bits and 48 kHz. Configure the AC-MB for USB audio as described in Section 6. As shown in Figure 6-6, select the audio serial bus tab.

GUID-18F49ECE-778E-4892-BFB8-7AC4B8BD9D9D-low.gifFigure 6-6 Audio Serial Bus Tab

In the ASI format configuration pane (shown in Figure 6-7), change the protocol format to I2S, and the word length to 16 bits.

GUID-4E7A5E41-6B5B-4130-8E3A-FE60A0B1769A-low.gifFigure 6-7 ASI Format Configuration

When the protocol format is changed to I2S in the GUI, the USB audio processor on the AC-MB also changes the audio format to I2S. The GUI reads the ASI status register (page 0 register 0x15), providing the detected sampling rate and BCLK and FSYNC ratio. The ASI status register can also be read manually in the audio serial bus tab by clicking the Read button, as shown in Figure 6-8, in the clock monitor pane.

GUID-114ACB8F-BA89-4D06-9F32-000C672F577E-low.gifFigure 6-8 Clock Monitor Pane

The default slot assignment for channel 1 is left slot 0 and the default slot assignment for channel 2 is left slot 1. As shown in Figure 6-9, change the channel 2 slot assignment to right slot 0. The diagram at the top of the window updates to display the data format and slots selected.

GUID-EF0188B7-4930-4613-AF09-6B10B26EE9C9-low.gifFigure 6-9 Channel Output Configuration and Diagram

The AC-MB USB audio currently supports only two channels per data line when in I2S mode and the BCLK and FSYNC ratio is fixed at 64. The EVM is now ready for use with the audio recording program of your choice.