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projectgus Merge branch 'bugfix/strict_prototypes' into 'master'
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Closes IDFGH-757

See merge request espressif/esp-idf!4546
Latest commit b237189 Aug 5, 2019

I2S Built-in ADC/DAC Example

(See the file in the upper level 'examples' directory for more information about examples.)

In this example, we configure I2S to work in I2S_ADC and I2S_DAC modes and then:

  • recording sound from ADC,
  • playing the recorded sound,
  • playing an audio file in flash via DAC.


The tools directory contains script for generating audio files:

* The script provides an example of generating audio tables from `.wav` files.
* In this example, the `wav` file must be in 16k/16bit mono format.
* The script will bundle the `wav` files into a single table named `audio_example_file.h`.
* Since the ADC can only play 8-bit data, the script will scale each 16-bit value to a 8-bit value.
* The script will covert all signed values into unsigned values because only positive values will be output by the ADC.

How to Use Example

Hardware Required

  • A development board with ESP32 SoC (e.g., ESP32-DevKitC, ESP-WROVER-KIT, etc.)
  • A USB cable for power supply and programming
  • A microphone (with amplifier) and one or two speaker(s) for testing.

The following is the hardware connection:

hardware module GPIO
Microphone ADC1_CH0 GPIO36
speaker(R) DAC1 GPIO25
speaker(L) DAC2 GPIO26

Configure the Project menuconfig
  • Set serial port under Serial Flasher Options, the flash size should be set to 4 MB.
  • Select "Custom partition table CSV" and rename "Custom partition CSV file" to "partitions_adc_dac_example.csv".

(Note that you can use sdkconfig.defaults)

Build and Flash

Build the project and flash it to the board, then run monitor tool to view serial output: -p PORT flash monitor

(To exit the serial monitor, type Ctrl-].)

See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.

Example Output

Reset your development board. The application it will first record the sound through the microphone. Then it will play the recorded sound, and finally a piece of audio stored in the flash. The following is the output log:

partiton addr: 0x00110000; size: 2097152; label: storage
Erasing flash
partiton addr: 0x00110000; size: 2097152; label: storage
Erase size: 323584 Bytes
I2S: PLL_D2: Req RATE: 16000, real rate: 1004.000, BITS: 16, CLKM: 83, BCK: 60, MCLK: 83.333, SCLK: 32128.000000, diva: 64, divb: 21
Sound recording 5%
Sound recording 10%
Sound recording 97%
Sound recording 102% 
playing: 0 %
playing: 1 %
playing: 2 %
playing: 96 %
playing: 97 %
playing: 98 %
Playing file example:
I2S: PLL_D2: Req RATE: 16000, real rate: 1004.000, BITS: 16, CLKM: 83, BCK: 60, MCLK: 83.333, SCLK: 32128.000000, diva: 64, divb: 21


  • Program upload failure

    • Hardware connection is not correct: run -p PORT monitor, and reboot your board to see if there are any output logs.
    • The baud rate for downloading is too high: lower your baud rate in the menuconfig menu, and try again.

For any technical queries, please open an issue on GitHub. We will get back to you soon.

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