This esp-idf-based application for the ESP32-LyraT reads stereo samples from the board's analog "AUX IN" input jack and outputs them through the "PHONE JACK" analog output again. It does so without all the overhead that esp-adf brings at the cost of not being as portable as esp-adf's pipeline_passthrough.
By default, this application uses a word length of 16 bits (bits per channel) and a sample rate of 44100kHz. It first configures the ES8388 audio codec chip on the ESP32-LyraT board through I²C and then transfers digital audio samples bidirectionally over I²S.
This project can be used as a starting point for implementing digital filters such as FIR / IIR / biquad filters and other digital signal processing (DSP) applications on the ESP32 plattform. The ESP32's Tensilica Xtensa processor architecture is well-know for its DSP capabilities. For instance, FIR filters can be efficiently implemented on the ESP32 thanks to support for special 16-bit multiply-accumulate instructions with optional parallel loading (MAC16 option for Tensilica Xtensa LX6).. See esp-dsp and the Xtensa Instruction Set Architecture (ISA) Reference Manual for more information.
Make sure to have a recent esp-idf version with support for cmake-based projects installed. Then compile and flash this project as usual using the following steps:
idf.py allto compile everything- Put your ESP32-LyraT into download mode: Press and hold
Boot, press and releaseRST, releaseBoot idf.py -p /dev/ttyUSBX flashto flash everything- Reset your ESP32-LyraT by pressing
RST
This project is licensed under the MIT license. See LICENSE for details.