ESPERDYNE — Ring Buffer & Dual-Channel Heterodyne (v1.1)

A pocketable, real-time heterodyne bat-call listener and “tap-to-save” field recorder built on ESP32-S3.

Licence: CC-BY-SA 4.0 • Author: Ravi Umadi • Date: August 2025

 What is ESPERDYNE?

ESPERDYNE is a high-fidelity, open-hardware/open-code bat detector for fieldwork and education. It provides dual-channel heterodyne monitoring at 192 kHz an on-device 5 s ring buffer in PSRAM, and a single-tap recording to microSD in WAV format. It’s designed for reliability in the field and accessibility in budget-limited contexts.

Key features

- Dual I²S: I2S0 input @ 192 kHz, I2S1 output @ 192 kHz.
- Stereo heterodyne with independent carrier frequencies per channel.
- Tap-to-save: write the last 5 s from the ring buffer to REC###.WAV
- OLED UI (128×32): file index, F/V mode, per-channel kHz, gain %, and MIX/ST status.
- Rotary encoder UX: fast frequency steps (default 5 kHz) or volume control.
- Mixing toggle: mono mix (MX) or true stereo (ST).
- File index scan on boot: avoids overwriting existing files.
- SdFat high-speed SPI writes.
- Runs on ESP32-S3 with 8 MB PSRAM and 16 MB flash.

Acknowledgements

Built as a derivative/companion tool to ongoing embedded ultrasonics work (e.g., BATSY4-Pro). Thanks to the open-source community (Espressif, Adafruit, billgreiman/SdFat) for superb libraries.

License

This project is licensed under the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) license.

Disclaimer

This code is provided as is without warranty. You are responsible for verifying functionality and ensuring safe and legal operation, especially in field or wildlife applications.