🚀 FluxSand is an interactive digital hourglass designed using real-time embedded systems. It combines gyroscope sensing, LED matrix display, and touch interaction to create a dynamic and visually engaging timekeeping experience. By leveraging advanced sensor fusion and real-time processing, this system responds seamlessly to user actions, providing an immersive interaction.

FluxSand utilizes sensor fusion technology and real-time processing to simulate a physical hourglass in a unique way:

• Smart Flow Effect: The LED matrix dynamically displays the movement of sand grains, adapting to device orientation.
• Multiple Modes:
  • Pomodoro Timer Mode
  • Temperature and Humidity Mode
  • Timing/Countdown Mode
• Enhanced Physical Interaction: Users can flip the device or use touch buttons to control functions like pause, speed adjustment, or reset.
• Adaptive Brightness: A light sensor detects ambient light levels and automatically adjusts LED brightness for optimal visibility.
• Audio Feedback: The buzzer provides audio cues when the countdown finishes or when switching modes, enhancing user experience.

📌 Key Technologies

• Event-driven programming: Uses callbacks to process sensor inputs & LED refresh, avoiding blocking operations and ensuring responsiveness.
• Multithreading control: Separates data acquisition & display updates for real-time performance.
• GitHub version control: Implements Git for version tracking, including commit history, issue tracking, and pull requests for structured development.

• Cong Liu (3055752L): Designed and implemented AHRS, systemd service integration, LED smoothing, and overall architecture control.
• Xinkai Li (3030890L): Integrated ADS1115 module; refactored and cleaned up third-party dependencies.
• Jiahe Chen (3049643C): Refined sensor fusion algorithms, improved inference runtime behavior, and optimized visual output handling.
• Haoming Wang (2987352W): Developed drivers for I2C peripherals including AHT20, BMP280, MAX7219; contributed to device interfacing.
• Lianxiao Yao (3048246Y): Developed GUI logic including countdown display, implemented motion-based flow behavior and fixed direction control.
• Yinjie Fan (3062833F): Implemented GUI components, humidity/temperature rendering, and contributed to LED matrix port control.

🔄 Hardware selection & procurement ························································································✅[Completed]
🔄 Initial code framework setup (C++ & sensor drivers) ···················································✅[Completed]
🔄 Optimization of real-time data processing ·········································································✅[Completed]
🔄 Enhancing user interaction (touch buttons & LED animation) ·································✅[Completed]
🔄 Software testing & debugging ··································································································✅[Completed]
📢 Project promotion (social media & Hackaday) ·································································✅[Completed]

✅ Real-time sensor data acquisition: The MPU-9250 gyroscope & accelerometer detect device orientation to control sand flow direction and speed.
✅ High-efficiency LED visual display: MAX7219 LED matrix presents fluid hourglass effects and weather information.
✅ Touch button interaction: Users can switch between different modes, such as a countdown timer or a weather clock.
✅ Smart brightness adjustment: The light sensor automatically modifies LED brightness based on ambient conditions.
✅ Audio feedback: The buzzer signals key events, such as countdown completion or mode changes.
✅ Temperature & air pressure detection: The AHT20 + BMP280 module measures ambient temperature and air pressure readings for the weather clock mode.

This project is developed primarily in C++, running on a Linux + Raspberry Pi platform, utilizing an event-driven real-time architecture to ensure seamless interactions.

📌 Code Structure

The source code is organized under the src/ directory as follows:

src/
├── main.cpp               # Main entry point of the program
├── ahrs/                  # AHRS (Attitude and Heading Reference System) algorithm module
│   ├── ahrs.cpp
│   └── ahrs.h
├── drivers/               # Hardware drivers
│   ├── mpu9250.cpp        # Driver for MPU9250 gyroscope and accelerometer
│   ├── mpu9250.h
│   ├── led_matrix.cpp     # Control logic for MAX7219 LED matrix
│   └── led_matrix.h
├── gui/                   # GUI and display logic
│   ├── display.cpp
│   └── display.h
└── utils/                 # Utility functions and common helpers
    ├── timer.cpp
    └── timer.h

Additional directories and files:

• third_party/libxr/: Integrated third-party library for extended functionality.
• imgs/: Visual assets and diagrams used in the README.
• .vscode/: Editor configuration files for VSCode development environment.
• .clang-format, .clangd: Code formatting and language server configuration.
• CMakeLists.txt: CMake configuration file for building the project.

🔹 Madgwick's filter: Madgwick algorithm for orientation estimation.

🔹 XRobot: An embedded software framework for MCU, Arm/x86 Linux and simulator.

🔹 Class Reference: A visual documentation of reference for classes.

🔹 Guide for Compile & Installation: A help documentation on how to compile and register as a system service.

Full program need to be compiled and installed on the Raspberry Pi 5B. But the unit test can be run on any Linux platform with onnxruntime.

🔹 Hardware References: This repository provides the complete set of Gerber files, drill data, and schematic required for manufacturing and testing a PCB design.

See this documentation to learn how we test and evaluate various modules of the system. This section provides an overview of testing and evaluation efforts conducted across various modules of the FluxSand system. The documentation focuses on real-time behavioral analysis of software components running on the Raspberry Pi platform. Preliminary sensor connection checks are included, while future work may involve expanded testing of hardware robustness and signal integrity.

🔹 Additional visual display modes, such as different sand animations or symbol-based representations.
🔹 Wireless remote control, allowing users to configure settings via WiFi/Bluetooth.
🔹 Data storage & visualization, enabling users to track historical temperature & air pressure readings via a web interface.

Documentation 📝
GitHub Repository 🔗
Demo Video 🎥
Social Media Promotion 📢