M5Stack IMU Data Recording System

A professional IMU sensor data logger for the M5Stack platform, featuring high-precision motion tracking with SD card storage.

Overview

This application interfaces with the MPU9250 9-axis IMU sensor to collect and log motion data from the M5Stack ESP32-based device. All sensor data is recorded to an SD card in CSV format for post-processing and analysis.

Features

• 9-Axis Motion Tracking: Records acceleration, gyroscope, and magnetometer data
• AHRS Mode: Real-time attitude estimation using Mahony quaternion filter
• SD Card Logging: Automatic CSV file creation and data logging
• Visual Feedback: LCD color indicators for system status
• Self-Calibration: Automatic sensor calibration on startup
• Temperature Monitoring: Integrated temperature sensor readings
• Diagnostic Logging: Self-test and calibration data for validation

Hardware Requirements

• M5Stack Core (ESP32-based)
• MPU9250 9-axis IMU sensor (integrated in M5Stack)
• SD card (FAT32 formatted)
• USB cable for programming and power

Sensor Data Output

The system creates the following CSV files on the SD card:

File	Contents	Units
acceleration.txt	3-axis acceleration data	milliGs (mg)
gyro.txt	3-axis gyroscope data	degrees/second
mag.txt	3-axis magnetometer data	milliGauss (mG)
quaternion.txt	Orientation quaternion (q0, qx, qy, qz)	unitless
ypr.txt	Yaw, Pitch, Roll angles	degrees
diagnostics.txt	Self-test and calibration data	various

System Operation

Startup Sequence

1. Blue Screen: System initialization (30-second stabilization delay)
2. Green Screen: Recording active
3. Red Screen: Error detected (check serial output for details)

Operating Modes

• AHRS Mode (default): Full attitude estimation with quaternion filtering
• Basic Mode: Simple sensor data output without attitude calculation

Configuration

Key configuration parameters in main.cpp:

#define AHRS_MODE_ENABLED true          // Enable AHRS attitude estimation
#define SERIAL_DEBUG_ENABLED true       // Enable serial debugging output
#define STARTUP_DELAY_MS 30000          // Startup stabilization time
#define AHRS_UPDATE_INTERVAL_MS 100     // AHRS data logging rate

Magnetometer Calibration

Environmental magnetic bias corrections are defined as:

#define MAG_BIAS_X 470.0f  // X-axis bias (milliGauss)
#define MAG_BIAS_Y 120.0f  // Y-axis bias (milliGauss)
#define MAG_BIAS_Z 125.0f  // Z-axis bias (milliGauss)

Note: These values should be calibrated for your specific environment and location.

Magnetic Declination

The default magnetic declination is set for SparkFun Electronics location:

• Location: 40°05'26.6"N, 105°11'05.9"W
• Declination: 8.5° E

Update MAGNETIC_DECLINATION_DEG for your location using NOAA Magnetic Field Calculator.

Building and Uploading

Prerequisites

• PlatformIO installed
• USB drivers for M5Stack (CH340/CP2104)

Build Instructions

# Build the project
pio run

# Upload to M5Stack
pio run --target upload

# Open serial monitor
pio device monitor

Upload Configuration

Default configuration uses COM5. To change the port, edit platformio.ini:

upload_port = COM[your_port_number]
monitor_port = COM[your_port_number]

Serial Monitor Output

When SERIAL_DEBUG_ENABLED is true, the system outputs real-time sensor data:

INFO: MPU9250 Self-Test Results:
  X-axis acceleration trim: 0.5% of factory value
  ...
ax = 1005 ay = -15 az = 980 mg
gx = 0.12 gy = -0.05 gz = 0.03 deg/s
mx = 45 my = -12 mz = 38 mG
Yaw, Pitch, Roll: 175.23, 1.45, -0.87
Update rate = 9.95 Hz

Code Quality

This project follows NASA C++ coding standards with emphasis on:

• Comprehensive documentation
• Clear naming conventions
• Proper error handling
• Modular function design
• Professional code formatting

Troubleshooting

Red Screen Error

• Check SD card is properly inserted and formatted (FAT32)
• Verify SD card has sufficient free space
• Check serial output for specific error messages

No Data Logging

• Verify SD card is not write-protected
• Check file system integrity
• Monitor serial output for file operation errors

Poor Orientation Accuracy

• Ensure 30-second startup stabilization completes
• Calibrate magnetometer bias values for your environment
• Keep device away from magnetic interference sources
• Update magnetic declination for your location

Contributing

Contributions are welcome! Please ensure code follows NASA C++ standards:

• Add comprehensive documentation
• Include error handling
• Use descriptive naming
• Maintain modular structure

License

See LICENSE file for details.

Version History

• v1.0 (2026-02-05): Initial release with NASA C++ standards compliance

Acknowledgments

Built on the M5Stack platform with MPU9250 IMU sensor integration and Mahony AHRS filter implementation.

Non professonal notes

wow 6 years later and my code ql has gotten so much better 🥳 yay! 🥳