RHYTHM open-source digital audio player features ESP32-S3 and ESS DAC

Probably Harmless has announced RHYTHM, an open-source digital audio player designed to provide a distraction-free music experience. The device focuses on local file playback from microSD cards, supporting formats such as MP3, FLAC, WAV, AAC, OGG Vorbis, and Opus at up to 24-bit/96 kHz.

Built on the ESP32-S3 microcontroller, the hardware includes high-end audio components like an ESS ES9038Q2M DAC and dedicated headphone amplifiers. The project aims to be fully open-source, with plans to release schematics, firmware, and 3D-printable enclosure designs during its upcoming crowdfunding campaign.

Hardware architecture and software stack

• Microcontroller and Memory: The system is powered by an ESP32-S3 MCU, supported by 16 MB of flash memory and 8 MB of PSRAM.
• Audio Signal Chain: High-fidelity output is achieved via an ESS ES9038Q2M 32-bit DAC, a Texas Instruments OPA1662 operational amplifier, and dual TPA6132A2 headphone amplifiers for independent 3.5 mm outputs.
• Software Framework: The firmware utilizes the ESP-IDF development framework, FreeRTOS for real-time operations, and the LVGL graphics library for the 320×240 color display.
• Extensibility: The hardware supports Retro-Go firmware, enabling the execution of classic NES and Game Boy titles, as well as Doom.
• Connectivity and Power: The device functions as a USB DAC for external computers and is powered by a 2,000 mAh lithium-polymer battery via USB-C.

Why it matters

By releasing complete schematics and firmware, RHYTHM provides a modular platform for hardware hackers and embedded developers to experiment with high-fidelity audio on the ESP32-S3. The inclusion of LVGL and FreeRTOS support makes it a practical reference design for those working with RTOS-based consumer electronics.