🐭 Open Source Micromouse Project

Welcome to the official repository of our Open Source Micromouse - a fast, intelligent, and compact maze-solving robot. This project aims to document every step of the design and development process, making it easy for students, hobbyists, and engineers to learn and contribute.

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🚀 Project Goal

To design and develop a four-wheel differential drive Micromouse robot capable of solving mazes efficiently with smooth acceleration, encoder feedback, and intelligent path planning - while maintaining openness for community learning and contribution.

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🧭 Table of Contents

• 🔍 Research & Reference Designs
• 🧩 Component Selection
• 📐 Mechanical Design
• ⚙️ Drive System
• 🔩 Drive System Assembly
• 🔌 Electronics & PCB Design
• 📦 Firmware Development
• 🖥️ Using the Mouse
• 🧠 Algorithms & Strategy
• 📸 Gallery
• 📚 Resources
• 🤝 Contributing
• 📜 License
• 📬 Contact & Support

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🔍 Research & Reference Designs

Before jumping into development, we explored multiple Micromouse designs, performance benchmarks, and open-source efforts.

• Ukmars
• Greenye (Good YouTube channel)
• Micromouse Online Handbook
• Speed Profile

📄 Design Inspirations

• Green-Giant

Reference images:

Reference Design 1	Reference Design 2

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🧩 Component Selection

Every part was chosen with precision to balance performance, weight, and efficiency.

Component	Description	Datasheet
MCU	STM32F405 (ARM Cortex-M4)	Datasheet
Motors	Coreless Motor 1215 with quadrature magnetic encoders	Buy
Encoders	Built-in quadrature magnetic encoders	-
IMU	ICM-42688	Datasheet
Sensors	TEFT4300 IR sensors with SFH4545	Datasheet
Power	2S Li-Po 250mAh	Buy

💡 Includes datasheets for all components in the Research/Datasheets folder.

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📐 Mechanical Design

• Designed in Onshape
• Lightweight 3D printable chassis
• Wheel size and placement optimized for turn radius

💡 Includes STL files for all parts in the Design/ folder.

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⚙️ Drive System

• Differential drive with PID-based velocity control
• Closed-loop motor control using encoders and gyro
• Acceleration curve implemented to avoid overshoot and wheel slippage

Drive Tuning

• ✔️ Encoder and Gyro feedback integrated
• ✔️ PWM control through timer
• ✔️ Slew rate limiter for smooth turns

Design Iterations

V1	V2	V3

Drive System — Design Evolution

• Initial concept: single driven wheel per side - very simple and lightweight, but limited in traction, torque, and fault tolerance.
• Iteration: switched to two wheels per side with proper gearing to share load, increase effective traction and torque, and add redundancy; gear ratio chosen for balanced acceleration and top speed.
• Optimization: integrated motor mounts and trimmed mounting hardware to reduce space and mass; components repositioned to lower the center of gravity and simplify wiring and belt/gear routing.
• Result: a compact, lightweight differential-drive assembly with improved performance, reliability, and manufacturability - documented trade-offs between complexity, weight, and available space.

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🔩 Drive System Assembly

Tools required: screwdriver and some patience :)

Components (extract)

1. Big gear and pins - harvested from an MG996R servo. You can either reuse the original gear pins or cut the servo screws and use those as compact pins (we need 4 of them).
2. Small gear - taken from an SG90 servo (we need 2 of them).
3. O-Rings - find them at your local hardware shop.
4. All other structural parts - 3D printed (mounts, spacers).

Step-by-step assembly

1. Prepare O-Rings, gears, and pins.
2. Fit O-Ring into the 3D printed rim.
3. Insert the pin/screw as shown in the figure.
4. Install the small gear on its printed mount and verify axial alignment with the big gear. Adjust spacers as needed for proper backlash (~0.1–0.3 mm).
5. Mount the motor.
6. Assemble the two-wheel side: place the wheels with pins into the mount.
7. Final check: rotate assembly by hand, verify smooth mesh, confirm no binding at extreme angles, and measure encoder counts while rotating to ensure correct coupling.

Figures

Fig 1 — Extracted MG996R big gear & pins	Fig 2 — Small gear from SG90
Fig 3 — Gears, pins, rim, and O-Ring	Fig 4 — Pin inserted into the rim and spacer
Fig 5 — Single side assembly	Fig 6 — Completed drive installation

Notes

• Keep gear mesh slightly loose to avoid binding under load.
• If using servo screws as pins, file the screw heads flush and secure with a small dab of adhesive.
• Document final spacer thicknesses for repeatable builds.

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🔌 Electronics & PCB Design

Designed using EasyEDA - a free tool for beginners. Our custom 2-layer PCB includes:

• STM32F405 MCU
• Power ICs
• Motor, encoder, and power connectors
• Motor drivers (DRV8833)
• Programming header (SWD)
• Debugging ports (UART)

Design	Soldered

💡 Includes relevant files in the PCB/ folder.

# PCB files and Gerbers:
PCB/
├── BOM.csv
├── micromouse.sch
└── gerbers/

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📦 Firmware Development

STM32CubeIDE Setup

1. Prerequisites

• Download and install STM32CubeIDE from STMicroelectronics.
• ST-Link USB debugger and drivers (or STMicro STM32CubeProgrammer for flashing).
• USB cable and target board powered.

2. Locate the project

• Open the repository and find the Firmware folder (Firmware/).
• Confirm structure: Core/ (Src, Inc), Drivers/, .ioc, Debug/ or Release/.

3. Import/open the project in STM32CubeIDE

• File → Import → General → Existing Projects into Workspace → select Firmware and finish.
• If there is a .ioc file, double-click it to open the CubeMX editor.

4. Using the provided init code

• The project already contains generated init functions (MX_GPIO_Init, MX_TIMx_Init, MX_USARTx_Init, etc.) in Core/Src (gpio.c, tim.c, usart.c).
• main.c calls these MX_* functions. Do not delete them.
• If you need to change pin assignments: edit the .ioc in CubeMX, re-generate code (Project → Generate Code). Keep user code within the USER CODE BEGIN/END blocks to avoid overwrites.

4.a Add Drivers include path

If you see missing headers from Core/Drivers/Inc, add the folder to the IDE include paths:

Project → Properties → C/C++ Build → Settings → Tool Settings → GCC C Compiler / GCC C++ Compiler → Includes

Add this include path (for both C and C++):

${workspace_loc:/${ProjName}/Core/Drivers/Inc}

5. Build the project

• Project → Build All (or Ctrl+B).
• Fix any MCU mismatch by verifying the target MCU in the .ioc or project properties.

6. Flashing and debugging

• Connect the board via ST-Link.
• Run → Debug As → STM32 Debugging (or Run As → STM32 C/C++ Application to run).
• Ensure target power and correct debug port (SWD).

7. Common notes & troubleshooting

• Preserve USER CODE BEGIN/END regions when regenerating code.
• If HAL symbols are missing, re-generate CubeMX code or enable the required middleware/peripherals in the .ioc.
• If pins appear wrong at runtime, verify .ioc pinout matches the board silkscreen/labeling and that MX_GPIO_Init is being called from main.c.

8. Quick checklist

• Firmware imported → .ioc verified → Generate (if changed) → Build → Connect ST-Link → Flash/Debug.

This will get the provided firmware building, pins initialized (via the generated MX_* init functions), and the code running on your STM32 target.

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🖥️ Using the Mouse

Basic Operation

• Once flashed, the mouse firmware will run automatically on power-up.
• The mouse should start tracking movement and button presses based on the configured sensors and GPIO pins.

Debugging via UART

For runtime debugging and configuration, you can communicate with the mouse over UART:

1. Hardware Setup

• Connect an HC-05 Bluetooth module to the UART TX/RX pins (refer to the PCB layout).
• Alternatively, use a USB-to-UART adapter directly connected to your PC.

2. Serial Communication Settings

• Baud rate: 115200
• Data bits: 8
• Parity: None
• Stop bits: 1

3. Mobile Debugging (Recommended)

• Pair your phone with the HC-05 Bluetooth module.
• Use a Serial Bluetooth terminal app (e.g., "Serial Bluetooth Terminal" on Android).
• Connect to the HC-05 device.

4. Available Commands

• Send help to display all available debug commands.
• Use the listed commands to inspect sensor values, test buttons, adjust sensitivity, or troubleshoot issues in real-time.

5. Example Workflow

> help
[List of commands appears]
> info
[Current mouse state and sensor readings]

This allows you to tune and debug the mouse behavior without reflashing the firmware.

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🤝 Contributing

We welcome contributions from the community! Whether you're fixing bugs, improving documentation, or adding new features:

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

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📜 License

This project is open-source for educational and non-commercial use only.

• Firmware: Licensed under GNU GPLv3
• Designs, PCBs, Images and Research Documentation: Licensed under CC-BY-NC-SA 4.0

You must:

• Credit RoboticGen (Pvt) Ltd when sharing or modifying.
• Release your derived works under the same license.
• Not use this work or any derivative for commercial purposes.

Example attribution:

Based on the RoboticGen (Pvt) Ltd Open Source Micromouse Project - OBO Mouse v4 (https://github.com/RoboticGen/obo-mouse-v4)

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🙏 Acknowledgements & The Team

This is not an overnight project. The current state of the Obo-Mouse v4 codebase is the culmination of years of consistent effort and tireless dedication by the robotics enthusiasts at RoboticGen. Everything you see here was built on the foundation of hands-on experience, countless iterations of building micromouse robots, and the invaluable knowledge gained from participating in competitions over the years.

A massive thank you to the team who made this open-source release possible:

Deepana

Seniru

Sanjula

Odil

Nimeth

Namina

Rajinthan

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📬 Contact & Support

Have questions or need help? Feel free to reach out!

• Issues: Open an issue on this repository
• Discussions: Join our community discussions

Happy building! 🐭🚀

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Made with ❤️ by the Sri Lankan Open Source Micromouse Team