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 https://github.com/SuperHouse/esp-open-rtos and https://github.com/pfalcon/esp-open-sdk/ 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 http://essentialscrap.com/esptalkie/ 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)
There is a script in tools/listen.py that can act as the other end of the connection, playing back sound using PC speakers.