22.6.2. I2S DMA

22.6.2.1. Overview

This example demonstrates the functionality of using I2S peripheral with DMA to transfer audio data and playback through the onboard codec.

Configure system audio clock (MCLK) according to the audio sampling rate
Configure I2S peripheral: - Enable MCLK output to Codec - Set audio data format (bit width, number of channels) - Configure DMA transfer mode - Enable DMA request
Configure Codec: - Set audio data format and sampling rate - Configure Codec to playback mode - Configure audio output path (e.g., headphone output)
Configure DMA: - Set source address to audio data buffer - Set destination address to I2S TX FIFO - Configure transfer size and width
Start I2S peripheral and DMA transfer: - Enable I2S peripheral - Start DMA transfer
DMA automatically transfers audio data to I2S TX FIFO
Disable DMA transfer and I2S peripheral when playback is complete

In CMakeLists.txt, set the appropriate audio codec type according to your board schematic:
- WM8960: set(CONFIG_CODEC "wm8960")
- SGTL5000: set(CONFIG_CODEC "sgtl5000")

On some development boards, there might be audio crosstalk when using the codec’s headphone interface. For example, when playing mono audio through the left channel, a faint sound might be heard in the right channel headphone.

Audio codec clock and configuration sequence:
- Most Audio codecs require MCLK from the I2S interface as their master clock source
- MCLK must be configured and enabled first before the codec’s working parameters can be configured through I2C interface

When the project runs correctly, you should observe:

Terminal output:

I2S DMA example
I2C bus is ready
i2s dma play finished