8b8 — 8-Bit 8asterd firmware

Arduino Leonardo driving three AY-3-8910A chips as a MIDI synth.

Layout

• 8b8_firmware.ino — the firmware
• generate.py — single source of truth for controllable parameters
• parameters.h — GENERATED. Do not edit by hand.
• index.html — GENERATED. Web Serial control panel (Chrome/Edge only).

Workflow

Edit PARAMS / PRESETS in generate.py, then:

python3 generate.py
arduino-cli compile --fqbn arduino:avr:leonardo .
arduino-cli upload -p /dev/ttyACM0 --fqbn arduino:avr:leonardo .

generate.py hashes the parameter definition into a layout-version byte. When that byte changes the firmware ignores any saved EEPROM bank and boots on defaults, so stale saves can never be misread as the new layout.

Open index.html directly in Chrome/Edge to control the unit. Close the tab before flashing or the upload will fail on a busy serial port.

Constraints

Leonardo (ATmega32u4): 28,672 bytes flash, 2,560 bytes RAM. RAM is the tight one — keep constant tables in PROGMEM and read them with pgm_read_*.

Struct definitions must stay above the first function definition in the .ino: the Arduino preprocessor inserts generated prototypes there, and a type declared later breaks the build.

License

Copyright © 2026 Greg Miller / The Key & Cable Company.

The firmware, browser emulator and tools are licensed under the GNU General Public License v3.0. You can use, study, share and modify it. If you distribute it or a modified version, you have to make the source available under the same licence.

The hardware design files (the v2 board in hardware/ on the v2/rp2040 branch, and front-panel artwork) are licensed under the CERN Open Hardware Licence Version 2 – Strongly Reciprocal (CERN-OHL-S-2.0). You can make, modify, sell and share hardware from them. If you share a modified design, or ship hardware made from one, you have to publish your design files under the same licence.

Source location: https://github.com/keyandcableco/8bit8asterd