IoTone
GitHub
What it is
MusicPixels turns an M5Stack Cardputer ADV into a self-contained generative synthesizer. Music plays from the Cardputer’s speaker; a transparent M5 Unit Glass (U158) OLED on the Grove port shows a different audio-reactive geometric scene for each genre; the LCD shows what’s playing. It’s the first project out of CardputerADV Hacking Japan, an IoTone hardware-hacking effort based in Fukuoka.
Four genres, never the same twice
| Genre | Character | Glass scene |
|---|---|---|
| Ambient | drumless pads, sparse bells, heavy delay | breathing polygons + note ripples |
| Downtempo | ~78–92 BPM swung drums, dub bass, e-piano | beat-expanding rings + orbiters |
| Synthwave | ~100–112 BPM four-on-the-floor, arps | scrolling perspective grid + sun |
| Classical | rubato generative piano, Alberti bass | Lissajous curves from the melody |
Every entry is re-seeded on selection, so a genre never plays the same way twice.
Under the hood
A 7-voice subtractive synth — polyBLEP oscillators, a TPT state-variable filter, ADSR, synthesized drums, a feedback delay, and a soft-clip master — renders in 256-sample blocks at 24 kHz on core 0 via M5Unified’s I2S/DMA speaker. A dual-“performance” bus lets genre switches crossfade over a second. The whole thing runs on the microcontroller; the Unit Glass is optional (the app shows “GLASS NOT FOUND” and keeps playing without it).
Status
Active. Build with PlatformIO (pio run) and launch from M5Launcher or flash over USB. Source on github.com/IoTone.