17. I2S EMULATION

17.1. Overview

  • This example project demonstrates the functionality of using SPI to emulate an I2S master for receiving audio decoding module recording data and playing back the recorded data.

  • The evaluation board must be connected to an audio decoding module. This example uses the WM8978 codec.

17.2. Tips

  • For detailed documentation about I2S over SPI, please refer to i2s_over_spi

17.3. Notice

  • Due to the requirement for long data transfers in this example, it is currently supported only on the hpm5300 series.

17.4. dependent components

  • dma_mgr

  • spi

  • i2s_over_spi

  • codec(wm8978)

17.5. Board Setting

  • Use the onboard microphone of the audio module for recording.

  • Connect a 3.5mm headphone to the audio module’s output headphone jack.

  • The following components are required: GPTMR output and SPI pins (Please refer to Pin Description )

  • Pin connections:

    • 5V <–> 5V(WM8978)

    • 3.3V <–> 3.3V(WM8978)

    • GND <–> GND(WM8978)

    • MCLK(GPTMR) <–> MCLK(WM8978)

    • LRCK(GPTMR) <–> (FSA)LRC(WM8978)

    • BLCK(GPTMR) <–> SCLK(SPI) <–> SCK(WM8978)

    • MISO(SPI) <–> (DAT)DACDATA(WM8978)

    • MOSI(SPI) <–> (SDB)ADCDATA(WM8978)

    • (CS)GPIO <–> CS(SPI)

    • I2C_SDA <–> I2C_SDA(WM8978)

    • I2C_SCL <–> I2C_SCL(WM8978)

17.6. Run steps

  • When the project runs correctly, the serial terminal will display the following menu:

---------------------------------------------------------------
*                                                             *
*                   i2s_emulation demo                        *
*                                                             *
*        1 - start play                                       *
*        2 - stop play                                        *
*        3 - start record                                     *
*        4 - stop record                                      *
*-------------------------------------------------------------*

  • Enter the character ‘3’ in the terminal to start recording. The system will automatically stop and save the recording when the duration exceeds the specified limit.

record_start enter....
recording size overflow, stopping and exiting now...

  • Enter the character ‘1’ in the terminal to start playback.

play start enter....
play end, now exit....

  • Enter the character ‘4’ in the terminal to stop recording.

record stop finish....

  • Enter the character ‘2’ in the terminal to stop playback.

play stop finish....