Raspberry Pi 4 IMU & Magnetometer Reader

A lightweight, robust, and dependency-minimal Python codebase for Raspberry Pi 4 to read real-time data from an IMU (MPU6050/MPU9250 at address 0x68) and a Magnetometer (HMC5883L/QMC5883L at address 0x1E).

Hardware Connection Guide

Connect both sensors to the Raspberry Pi 4 I2C bus as follows:

Sensor Pin	Pi 4 GPIO Pin	Description
VCC	Pin 1 (3.3V)	Power Supply
GND	Pin 9 (Ground)	Common Ground
SDA	Pin 3 (SDA / GPIO 2)	Serial Data Line
SCL	Pin 5 (SCL / GPIO 3)	Serial Clock Line

Note: Since I2C is a shared bus, both sensors can be wired in parallel to the same SDA and SCL pins on the Raspberry Pi.

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Software Setup

1. Enable I2C on Raspberry Pi

Open the Raspberry Pi terminal and open the configuration tool:

sudo raspi-config

Navigate to Interface Options -> I2C and select Yes to enable the I2C interface. Reboot your Pi:

sudo reboot

2. Verify I2C Connections

Install i2c-tools to check if the Pi detects the sensors:

sudo apt-get install -y i2c-tools

Run i2cdetect to scan the bus:

i2cdetect -y 1

You should see output indicating devices are present at address 1e and 68:

     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- -- 
10:  -- -- -- -- -- -- -- -- -- -- -- -- -- -- 1e -- 
20:  -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30:  -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40:  -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50:  -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60:  -- -- -- -- -- -- -- -- 68 -- -- -- -- -- -- -- 
70:  -- -- -- -- -- -- -- --                        

3. Install Dependencies

Install Python dependencies using the provided requirements.txt:

pip install -r requirements.txt

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Running the Code

1. Run 3D Web Visualization Server (Interactive Web Dashboard)

To launch the interactive 3D WebGL Dashboard with real-time trajectory visualization, run:

python web_server.py

Then open http://localhost:8000 in your web browser.

2. Run CLI Console Receiver (Optional)

To view raw text telemetry in your terminal, run:

python client.py

3. Run Sensor Publisher (on the Raspberry Pi)

Execute the main script to start streaming sensor readings:

python main.py

Key Customization

In main.py, you can customize:

• DECLINATION_ANGLE_DEG: Set this to get accurate true-north headings based on your location. Find your declination angle at magnetic-declination.com.
• UDP_IP: Target IP address to send sensor data (e.g., target laptop's IP, or "255.255.255.255" for local network broadcast).
• UDP_PORT: Port number for UDP transmission (default is 5005).

UDP Payload format (6DoF Pose Estimation)

The payload is sent as a JSON string with the following structure:

{
  "timestamp": 1721389811.234,
  "dt": 0.02,
  "rotation": {
    "quaternion": {"w": 0.99, "x": 0.01, "y": 0.02, "z": -0.05},
    "euler": {"roll": 1.2, "pitch": 2.3, "yaw": -5.7}
  },
  "translation": {
    "position": {"x": 0.12, "y": -0.05, "z": 0.01},
    "velocity": {"x": 0.01, "y": -0.00, "z": 0.00},
    "linear_accel": {"x": 0.05, "y": -0.02, "z": 0.01}
  },
  "heading": 85.3,
  "raw_imu": {
    "accel": {"x": 0.01, "y": -0.02, "z": 0.98},
    "gyro": {"x": 0.1, "y": -0.2, "z": 0.05},
    "mag": {"x": -2.3, "y": 25.1, "z": -40.2},
    "temp": 28.5
  }
}