Eidon tracker

Eidon Tracker

A complete Bluetooth IMU tracking system featuring custom hardware, 3D printed enclosure, and web-based applications. The Eidon Tracker transmits real-time quaternion orientation data over Bluetooth HID, making it perfect for motion capture, gaming, and interactive applications.

Features

• High-precision IMU tracking with BNO085 9-DOF sensor
• Bluetooth HID device - appears as standard input device
• Real-time quaternion data streaming at 1000Hz
• Custom 3D printed enclosure with integrated switches
• Web-based applications for visualization and interaction
• Battery monitoring with charging status
• Device color customization via HID feature reports

Bill of Materials (BOM)

Required Components

3D Printing Materials

Tools Required

• 3D Printer
• Soldering iron and solder
• Small screwdriver
• Wire strippers

Estimated Total Cost: $80-120 USD

Hardware Setup

Wiring Diagram

Connect the BNO085 to the XIAO nRF52840 Sense:

Switch Connections

3D Printing

Print the following files from the cad/ directory:

1. eidon-tracker-base.stl - Main enclosure base
2. eidon-tracker-top.stl - Enclosure lid
3. eidon-tracker-mount.stl - Optional mounting bracket

Print Settings:

• Layer Height: 0.2mm
• Infill: 20%
• Support: Yes (for overhangs)
• Material: PLA

Software Setup

PlatformIO Installation

1. Install Visual Studio Code
2. Install the PlatformIO IDE extension

Building and Uploading Firmware

1. Clone this repository:

   git clone https://github.com/yourusername/eidon-tracker.git
   cd eidon-tracker

2. Open the project in VSCode with PlatformIO

3. Connect your XIAO nRF52840 Sense via USB

4. Build and upload:

   pio run --target upload

Dependencies

The following libraries are automatically managed by PlatformIO:

• Adafruit BNO08x (v1.2.3+) - IMU sensor driver
• Adafruit BluefruitLE nRF52 - Bluetooth functionality
• Arduino Framework - Core functionality

Web Applications

The web/ directory contains the main interactive application:

3D Orientation Visualizer (index.html)

• Real-time 3D visualization of tracker orientation and movement
• Multiple camera angles and viewing modes
• Bluetooth HID integration for seamless device connectivity
• Calibration status monitoring and quaternion data display

Running Web Applications

Simply open web/index.html directly in your web browser:

1. Navigate to the web/ directory in your file explorer
2. Double-click index.html to open it in your default browser
3. Or right-click and "Open with" your preferred browser (Chrome/Edge recommended for Web Bluetooth support)
4. Connect to your Eidon Tracker via Bluetooth

HID Reports

The Eidon Tracker implements a custom HID device with multiple report types for data exchange:

Input Report (Report ID: 1)

Size: 9 bytes total

• Quaternion Data (8 bytes): Four 16-bit values representing orientation
  • w component (bytes 0-1): Scalar part of quaternion
  • x component (bytes 2-3): X-axis rotation
  • y component (bytes 4-5): Y-axis rotation
  • z component (bytes 6-7): Z-axis rotation
• Switch States (1 byte): Two button states plus padding
  • Bit 0: Left/Right switch state
  • Bit 1: Upper/Lower switch state
  • Bits 2-7: Reserved (padding)

Output Report (Report ID: 1)

Size: 1 byte

• Vendor Command: Custom command byte for device control
  • Used for device configuration and special commands
  • Values defined in firmware for various operations

Feature Report (Report ID: 1)

Size: 3 bytes

• RGB Color Settings: Device LED color configuration
  • Byte 0: Red component (0-255)
  • Byte 1: Green component (0-255)
  • Byte 2: Blue component (0-255)
  • Colors are stored in device flash memory
  • Allows customization of device LED color

HID Usage Pages

• Primary: Sensor Page (0x20) - Orientation Usage (0x80)
• Secondary: Button Page (0x09) - Button 1-2
• Vendor: Custom Page (0xFF00) - Vendor-specific features

Usage

Initial Setup

1. Power on the device - LED will indicate status
2. Pair via Bluetooth - Device appears as "Eidon Tracker XXXX"
3. Calibrate IMU - Wave device in figure-8 pattern until calibrated
4. Open web application of choice
5. Connect to device in web browser

Calibration Process

The BNO085 sensor requires calibration for optimal performance:

1. Gyroscope: Keep device stationary for 2-3 seconds
2. Accelerometer: Slowly rotate through all orientations
3. Magnetometer: Move device in figure-8 pattern away from magnetic interference
4. Monitor calibration status in web application or serial output

LED Status Indicators

Development

Project Structure

eidon-tracker/
├── firmware/               # PlatformIO firmware project
│   ├── src/main.cpp       # Main firmware source
│   ├── platformio.ini     # PlatformIO configuration
│   └── lib/               # Custom libraries
├── web/                   # Web applications
│   ├── index.html         # 3D orientation visualizer
│   └── script.js          # Shared JavaScript libraries
├── cad/                   # 3D printing files
│   ├── eidon-tracker.f3d  # Fusion 360 source
│   ├── *.stl              # STL files for printing
│   └── *.gcode            # Pre-sliced files
├── images/                # Product photos
└── README.md              # This file

Firmware Development

The firmware is built on the Arduino framework with PlatformIO. Key components:

• HID Report Descriptor: Custom HID device with quaternion data
• Bluetooth Stack: Adafruit Bluefruit nRF52 library
• IMU Driver: Adafruit BNO08x library
• Battery Management: Built-in XIAO charging and monitoring

Adding New Web Applications

1. Create new HTML file in web/ directory
2. Include script.js for Bluetooth connectivity
3. Implement HID report parsing for quaternion data
4. Add visualization or interaction logic

Troubleshooting

Connection Issues

• Device not found: Ensure Bluetooth is enabled and device is in pairing mode
• Connection drops: Check battery level and distance from host device
• Web Bluetooth not supported: Use Chrome/Edge on desktop or Android

Calibration Problems

• Poor tracking accuracy: Ensure proper IMU calibration
• Drift over time: Recalibrate magnetometer away from metal objects
• Erratic behavior: Check wiring connections and power supply

Build Issues

• Platform not found: Ensure Seeed nRF52 platform is properly installed
• Library conflicts: Clean build environment with pio run --target clean
• Upload fails: Double-tap reset button to enter DFU mode

Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Test thoroughly
5. Submit a pull request

License

This project is open source and available under the MIT License. See LICENSE file for details.

Acknowledgments

• Seeed Studio for the excellent XIAO nRF52840 Sense board
• Adafruit for comprehensive sensor libraries and breakout boards
• PlatformIO for the excellent development environment