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Software for a ESP8266 based walkie talkie radio (doesn't work very well)
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tools Audio output, power button May 31, 2018
fast_adc.h Basic audio sending May 3, 2018
sigma_delta.c Audio output, power button May 31, 2018
sigma_delta.h Audio output, power button May 31, 2018
user_main.c Add echo cancellation and noise removal Jul 16, 2018

ESP8266 Walkie Talkie

This is a somewhat failed attempt to make a ESP8266 based two-way radio. It fails due to ESP8266 causing a lot of radio noise in the audio signals.


  • alaw.c: Implementation of A-law audio compression algorithm.
  • audio_task.c: Main logic for audio capture and playback and network connection
  • fast_adc.c: Fast ADC implementation (up to ~20kHz samplerate)
  • sigma_delta.c: Sigma-delta modulation for audio playback
  • user_main.c: Startup logic, volume control and wifi passwords.


To build the firmware, you need and installed.

Make sure that esp-open-sdk is in your PATH environment variable.

If needed, edit ESP_OPEN_RTOS_DIR in Makefile.

Then just type make to build or make flash to also program the ESP8266.


See for more details, but for basic testing you can connect:

  • GPIO3 / RXD to speaker
  • TOUT / ADC0 to output from microphone amplifier (0..1V voltage level)

Testing with PC

There is a script in tools/ that can act as the other end of the connection, playing back sound using PC speakers.

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