DIVINER open firmware turns M5 Cardputer into multi-function synth and scanner

DIVINER is a newly released open-source firmware project for the M5 Cardputer, an ESP32-S3-based handheld development kit with a keyboard, small display, GPIO, I2C, and an audio jack. The firmware transforms the device into a multi-function tool serving as a standalone synthesizer and sequencer using I2S audio output, a visualization engine, a WiFi and Bluetooth scanner and monitor, an LLM interface, and an IR blaster. The project also implements Channel-State Information processing for presence detection and includes a byte-beat player. A simulator is available for testing while hardware ships.

The firmware is structured around a system layer with applications called "rites," each following a unified "blood and ember" visual aesthetic reminiscent of the Diablo game series. The Hackaday.io project page emphasizes the underlying system architecture before describing individual applications, suggesting the diverse feature set was designed to exercise and demonstrate the capabilities of the base firmware layer.

Hardware platform and firmware architecture

• SoC: M5 Cardputer is built around the ESP32-S3, a dual-core Xtensa LX7 microcontroller with Wi-Fi 4 and Bluetooth 5 LE connectivity.
• Audio subsystem: The synthesizer and sequencer use I2S digital audio output through the device's built-in audio jack, with the firmware implementing a complete audio engine.
• Wireless capabilities: The firmware includes WiFi and Bluetooth scanning and monitoring functions, plus Channel-State Information exploitation for presence detection without dedicated radar hardware.
• I/O interfaces: The firmware leverages GPIO, I2C, and an IR LED for the blaster functionality, alongside the integrated keyboard and display for user interaction.
• System architecture: Applications are modular "rites" running on a shared system layer, with a PC-based simulator available for development and testing without physical hardware.

Why it matters

DIVINER demonstrates the continued viability of the ESP32-S3 as a platform for complex, multi-function open-source firmware that goes far beyond typical IoT sensor applications. For open hardware enthusiasts and embedded developers, the project's modular "rites" architecture and available simulator provide a reference for building sophisticated applications on low-cost, widely available dev kits. The combination of audio synthesis, wireless analysis, and AI interfaces in a single open firmware also highlights how hobbyist-grade hardware can serve as an accessible testbed for integrating disparate technologies that are typically siloed in commercial products.