A buttonless Arduino-based Pomodoro timer housed in a handcrafted wooden shell. The device reads its own orientation via an accelerometer — flipping it to a different face starts a different countdown. No buttons, no touchscreen, no app required.
Built as an alternative to software timers that compete for screen real estate and attention. A physical object on a desk, with no screen of its own, is a more effective focus anchor than yet another browser tab or phone notification.
- Preview
- Live Simulation
- Features
- Tech Stack and Hardware
- Design Decisions
- Project Structure
- Getting Started
- Usage
- Configuration and Environment
- Contributing
- License
| 3D Model Overview | Panels and Exploded View |
|---|---|
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| Inner Core | Top-Down Layout |
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| State | Trigger | LED |
|---|---|---|
| Timer Active | Face 1/2/3/4 pointing up — sets 5, 15, 25, or 45 min | Green |
| Warning | 30 seconds remaining | Blinking Yellow |
| Time's Up | Countdown reached 00:00 | Blinking Red |
| Paused | Screen face pointing straight up (Z-axis) | Blue |
| Idle | No face detected yet | Off |
| Timer Active | Warning | Time's Up | Paused | Idle |
|---|---|---|---|---|
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No hardware required to test the firmware. Run the exact sketch in your browser via Wokwi:
Run the Virtual Prototype on Wokwi
In the simulation: click the switch to power on, then click the blue MPU6050 sensor block to change the X/Y/Z axis values and observe the OLED and LED react in real time.
- Buttonless operation — physical orientation is the only input, read directly from the MPU6050 accelerometer
- Four preset countdowns mapped to faces: 5, 15, 25, and 45 minutes
- Pause face (Z-axis up) freezes the countdown without resetting — flip back to resume exactly where it left off
- OLED content rotates automatically to match the orientation of the active face
- RGB LED feedback: green (running), blinking yellow (last 30s), blinking red (done), blue (paused), off (idle)
- Delta-time countdown via
millis()— accurate regardless of main loop execution speed
Firmware
- Language: C++ (Arduino framework,
.ino) - Libraries:
Wire.h,Adafruit_MPU6050,Adafruit_Sensor,Adafruit_GFX,Adafruit_SSD1306
Hardware
| Component | Spec |
|---|---|
| Microcontroller | Arduino Nano / Pro Micro |
| Motion Sensor | MPU6050 — 6-axis accelerometer and gyroscope, I2C |
| Display | SSD1306 OLED, 128×64, I2C |
| Visual Feedback | RGB LED (Common Cathode) + 3× 330Ω resistors |
| Power Management | TP4056 LiPo charging module |
| Power Source | 3.7V LiPo battery |
| Enclosure | Custom handcrafted wooden shell |
Why no buttons? Physical buttons require deliberate action — you press them because you decided to. Orientation-based input is lower friction for mode switching and naturally maps to a cube's faces in a way that's instantly learnable without documentation. In practice, flipping the cube to start a new session creates a small physical ritual that reinforces the focus intent.
Why millis() instead of a blocking delay()? delay() halts execution, which would make the device unresponsive to orientation changes mid-countdown. The delta-time pattern (millis() minus last-tick) allows the main loop to keep polling the accelerometer every cycle while still tracking elapsed time accurately.
Why an acceleration threshold of 7.0? This value was determined empirically during testing on the specific enclosure. The cube needs to be held fairly steady to register a face — incidental tilts while moving it across a desk don't trigger a timer switch. If you rebuild this with a different enclosure or mount the sensor differently, you may need to retune this constant.
PomodoroGravityCube/
├── src/
│ └── cubo_pomodoro.ino # Firmware — orientation, timer logic, OLED and LED output
├── assets/
│ ├── back.png
│ ├── blu.png
│ ├── front.png
│ ├── giallo.png
│ ├── rosso.png
│ ├── side.png
│ ├── spento.png
│ ├── up.png
│ └── verde.png
├── README.md
└── LICENSE
- Arduino IDE (1.8+ or 2.x) or PlatformIO
- Hardware components listed above, wired to the microcontroller
- The following libraries installed via the Arduino Library Manager:
Adafruit MPU6050Adafruit Unified SensorAdafruit GFX LibraryAdafruit SSD1306
git clone https://github.com/mirconegri/PomodoroGravityCube.git
cd PomodoroGravityCubeWire the MPU6050 and SSD1306 to the microcontroller's I2C bus (SDA/SCL). Wire the RGB LED to three PWM-capable digital pins through 330Ω resistors. Refer to the diagrams in assets/ for the breadboard layout.
Open src/cubo_pomodoro.ino in the Arduino IDE, select your board and port, and upload.
Once powered on:
- Flip to Face 1, 2, 3, or 4 → starts a 5, 15, 25, or 45-minute countdown
- Flip to Z-axis up (screen face up) → pauses the current timer without losing progress
- Flip back to the same face → resumes from where it paused
- Flip to a different face mid-session → starts a fresh countdown for the new duration
- When the display shows "FINITO!" → flip to any face to reset and start a new session
No environment variables or configuration files. All tunable values are constants in src/cubo_pomodoro.ino:
| Constant | Current Value | Purpose |
|---|---|---|
pinRosso, pinVerde, pinBlu |
5, 6, 9 |
RGB LED output pins |
| Per-face durations | 5 / 15 / 25 / 45 min | Set in the switch (facciaAttuale) block |
| Acceleration threshold | 7.0 |
Sensitivity for face detection — tune if mounting differs |
Contributions welcome — firmware improvements, alternative enclosure designs, or wiring variants:
- Fork the repository
- Create a feature branch (
git checkout -b feature/your-feature) - Commit your changes with a clear message
- Open a Pull Request
For bugs or ideas, open an Issue.
Mirco Negri — Computer Science @ UniTrento
This project is licensed under the MIT License — see the LICENSE file for details.