MusicPixels — a generative synth on the M5 Cardputer ADV + Unit Glass

We kicked off CardputerADV Hacking Japan — an IoTone hardware-hacking effort out of Fukuoka — with its first project, MusicPixels.

MusicPixels turns an M5Stack Cardputer ADV into a stand-alone generative synthesizer. Music plays from the built-in speaker; a transparent M5 Unit Glass (U158) OLED on the Grove port renders a different audio-reactive geometric scene per genre; the LCD shows what’s playing.

Four genres, re-seeded every time

Ambient (breathing polygons + note ripples), Downtempo (beat-expanding rings), Synthwave (a scrolling perspective grid + sun), and Classical (Lissajous curves drawn from the melody). Each is re-randomized from a fresh seed on selection, so it never plays the same way twice, and genre switches crossfade over a second.

What’s inside

A 7-voice subtractive synth — polyBLEP oscillators, a TPT state-variable filter, ADSR, synthesized drums, feedback delay, and a soft-clip master — renders in 256-sample blocks at 24 kHz on core 0 via M5Unified’s I2S/DMA speaker. It runs entirely on the microcontroller; the Unit Glass is optional (no Glass, no problem — the music and LCD keep going).

Build with PlatformIO and launch from M5Launcher, or flash over USB. Source on github.com/IoTone.