Bare-metal C firmware that turns an ATtiny85 into a three-speed electric-toothbrush controller.
Short press → cycle speeds · Long press → start / stop & ultra-low-power sleep
| Category | Highlights |
|---|---|
| ⚙️ Deterministic PWM | Phase-correct 8-bit PWM via Timer0 (~16 kHz) for smooth motor control |
| 🚀 Three Speed Levels | Lookup table for 100%, 66%, and 33% motor duty cycles |
| 🖲️ One-Button UI | INT0-based ISR distinguishes between short and long presses |
| 🔋 Ultra-Low Power | < 5 µA in SLEEP_MODE_PWR_DOWN mode for long battery life |
| 🧩 Modular Drivers | Clean, decoupled APIs for motor, button, and power subsystems |
| 🔄 Continuous Build | GitHub Actions CI on every push to main |
This project is a minimal but robust firmware for DIY or commercial electric toothbrush designs. It emphasizes low power consumption, predictable timing, and user-friendly control, while sticking to bare-metal C for full control over performance and size.
Ideal for:
- Battery-powered personal care devices
- Hobby projects involving brushed DC motors
- Learning AVR low-level development
git clone https://github.com/dondfx/attiny85-toothbrush.git
cd attiny85-toothbrush
platformio run # builds firmware.hex
platformio run -t upload # flash with USBtinyISPEnsure proper clock and power behavior by burning the correct fuses:
LFUSE 0xE2 HFUSE 0xD7 EFUSE 0xFF
To burn the fuses, use this command (replace -c usbtiny if you're using a different programmer):
avrdude -p attiny85 -c usbtiny -U lfuse:w:0xE2:m -U hfuse:w:0xD7:m -U efuse:w:0xFF:m
attiny85-toothbrush/
├── include/ → Header files (motor.h, button.h, power.h)
├── src/ → Source code: drivers + main
├── hardware/
│ ├── gerbers/ → PCB manufacturing files
│ ├── step/ → 3D STEP model of the PCB
│ └── docs/ → Wiring diagram & connection info (PDF)
├── .github/ → GitHub Actions CI workflow
├── platformio.ini → PlatformIO project config
├── BOM.md → Bill of Materials with footprints
└── README.md → This documentation
- MCU: ATtiny85 @ 8 MHz (internal RC oscillator)
- Output: PB0 (OC0A) → Motor PWM control
- Input: PB2 (INT0) → Single button
- Power Mode: Enters SLEEP_MODE_PWR_DOWN after 2 s long press
✅ Stable & tested on breadboard and custom PCB
✅ < 5 µA sleep current
🔄 Future: H-bridge motor driver support (e.g., DRV8833)
This project is licensed under the MIT License.
Built for fun, learning, and real-world utility. Contributions welcome!