Tag Archives: QMC5883L

In this video lesson we show how to easily calibrate a 9-axis IMU. We are using the GY-87 IMU module which contains a MPU6050 for measuring acceleration and rotational velocity, and the QMC5883L magnetometer. In this work, we have three programs. The first is simple arduino program for measuring and printing the data from the 9 sensors. Then, the second program is a python program on your PC which will allow you to simply and accurately calibrate the 9 sensors, from the data coming from the first program. Then the third program is a program on the arduino that reads the data from the sensors, and then uses the calibration data that was generated to create accurate, calibrated sensor data.

This is the schematic of the circuit we are working with:

Then this is the arduino code we use to calibrate the sensors:

#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>
#include <Wire.h>
#include <QMC5883LCompass.h>
float AxRaw,AyRaw,AzRaw,GxRaw,GyRaw,GzRaw,MxRaw,MyRaw,MzRaw;
Adafruit_MPU6050 mpu;
QMC5883LCompass compass;

void setup() {
  // put your setup code here, to run once:
Serial.begin(115200);
mpu.begin();
mpu.setI2CBypass(true);
compass.init();
mpu.setGyroRange(MPU6050_RANGE_1000_DEG);
delay(100);
}

void loop() {
  // put your main code here, to run repeatedly:
compass.read();
sensors_event_t a, g, temp;
mpu.getEvent(&a, &g, &temp);

AxRaw = a.acceleration.x;
AyRaw = a.acceleration.y;
AzRaw = a.acceleration.z;

GxRaw = g.gyro.x;
GyRaw = g.gyro.y;
GzRaw = g.gyro.z;

MxRaw= compass.getX();
MyRaw= compass.getY();
MzRaw= compass.getZ();

Serial.print(AxRaw);
Serial.print(',');
Serial.print(AyRaw);
Serial.print(',');
Serial.print(AzRaw);
Serial.print(',');
Serial.print(GxRaw);
Serial.print(',');
Serial.print(GyRaw);
Serial.print(',');
Serial.print(GzRaw);
Serial.print(',');
Serial.print(MxRaw);
Serial.print(',');
Serial.print(MyRaw);
Serial.print(',');
Serial.println(MzRaw);
delay(100);
}

#include <Adafruit_MPU6050.h>

#include <Adafruit_Sensor.h>

#include <Wire.h>

#include <QMC5883LCompass.h>

float AxRaw,AyRaw,AzRaw,GxRaw,GyRaw,GzRaw,MxRaw,MyRaw,MzRaw;

Adafruit_MPU6050 mpu;

QMC5883LCompass compass;

void setup() {

// put your setup code here, to run once:

Serial.begin(115200);

mpu.begin();

mpu.setI2CBypass(true);

compass.init();

mpu.setGyroRange(MPU6050_RANGE_1000_DEG);

delay(100);

}

void loop() {

// put your main code here, to run repeatedly:

compass.read();

sensors_event_t a, g, temp;

mpu.getEvent(&a, &g, &temp);

AxRaw = a.acceleration.x;

AyRaw = a.acceleration.y;

AzRaw = a.acceleration.z;

GxRaw = g.gyro.x;

GyRaw = g.gyro.y;

GzRaw = g.gyro.z;

MxRaw= compass.getX();

MyRaw= compass.getY();

MzRaw= compass.getZ();

Serial.print(AxRaw);

Serial.print(',');

Serial.print(AyRaw);

Serial.print(',');

Serial.print(AzRaw);

Serial.print(',');

Serial.print(GxRaw);

Serial.print(',');

Serial.print(GyRaw);

Serial.print(',');

Serial.print(GzRaw);

Serial.print(',');

Serial.print(MxRaw);

Serial.print(',');

Serial.print(MyRaw);

Serial.print(',');

Serial.println(MzRaw);

delay(100);

}

This next program is to be run on your PC. It is a python program that will read the data coming from the arduino, and will then help you calibrate your sensors.

import serial
import numpy as np
from PyQt5 import QtWidgets, QtCore, QtGui
import pyqtgraph as pg
import pyqtgraph.opengl as gl
from pyqtgraph.opengl import GLViewWidget, GLLinePlotItem, GLMeshItem
import time
import os
import math# --- Serial Port Configuration ---
# Strategy: Set up serial communication with the IMU to receive raw sensor data:
# ax, ay, az (m/s²), gx, gy, gz (rad/s), mx, my, mz (arbitrary units from QMC5883L).
# Convert gyro data to °/s immediately after reading for consistency with plots and calibration.
serialPort = 'COM8'  # Serial port for IMU communication (adjust as needed)
baudRate = 115200  # Baud rate matching IMU configuration
timeout = 0.1  # Serial read timeout in seconds
accMagMaxPoints = 1000  # Max points for accelerometer/magnetometer plots
gyroMaxPoints = 100  # Max points for gyroscope plots
trailMaxPoints = 100  # Max points for 3D magnetic trail
gyroTimeWindow = 5.0  # Time window for gyro plots in seconds
alpha = 0.3  # Low-pass filter constant for smoothing accelerometer/magnetometer data
epsilon = 1e-6  # Small constant to prevent division by zero in calculations# --- Calibration Variables ---
# Strategy: Store calibration parameters to correct sensor biases and scales.
# Gyro offsets are in °/s (converted from rad/s on input).
# Accelerometer in m/s², magnetometer in µT after calibration.
gxOffset = 0.0  # Gyroscope x-axis offset (°/s)
gyOffset = 0.0  # Gyroscope y-axis offset (°/s)
gzOffset = 0.0  # Gyroscope z-axis offset (°/s)
accCalibrating = False  # Flag for accelerometer calibration mode
magCalibrating = False  # Flag for magnetometer calibration mode
accMin = {'x': float('inf'), 'y': float('inf'), 'z': float('inf')}  # Min accelerometer readings (m/s²)
accMax = {'x': float('-inf'), 'y': float('-inf'), 'z': float('-inf')}  # Max accelerometer readings (m/s²)
magMin = {'x': float('inf'), 'y': float('inf'), 'z': float('inf')}  # Min magnetometer readings (arb. units)
magMax = {'x': float('-inf'), 'y': float('-inf'), 'z': float('-inf')}  # Max magnetometer readings (arb. units)
magRawMin = {'x': float('inf'), 'y': float('inf'), 'z': float('inf')}  # Min raw magnetometer readings
magRawMax = {'x': float('-inf'), 'y': float('-inf'), 'z': float('-inf')}  # Max raw magnetometer readings
accOffset = {'x': 0.0, 'y': 0.0, 'z': 0.0}  # Accelerometer offsets (m/s²)
accScale = {'x': 1.0, 'y': 1.0, 'z': 1.0}  # Accelerometer scales
magOffset = {'x': 0.0, 'y': 0.0, 'z': 0.0}  # Magnetometer offsets (arb. units)
magScale = {'x': 1.0, 'y': 1.0, 'z': 1.0}  # Magnetometer scales (to µT)
accFiltered = {'x': None, 'y': None, 'z': None}  # Filtered accelerometer data (m/s²)
magFiltered = {'x': None, 'y': None, 'z': None}  # Filtered magnetometer data (arb. units)
axSamples = []  # Accelerometer x-axis samples during calibration
aySamples = []  # Accelerometer y-axis samples during calibration
azSamples = []  # Accelerometer z-axis samples during calibration
mxSamples = []  # Magnetometer x-axis samples during calibration
mySamples = []  # Magnetometer y-axis samples during calibration
mzSamples = []  # Magnetometer z-axis samples during calibration
trailBuffer = []  # Buffer for 3D magnetic vector trail# --- Data Storage ---
# Strategy: Store raw and calibrated sensor data in numpy arrays for efficient plotting.
# Gyro data is stored in °/s after conversion from rad/s.
accRaw = {'x': np.empty(0), 'y': np.empty(0), 'z': np.empty(0)}  # Raw accelerometer data (m/s²)
gyroRaw = {'x': np.empty(0), 'y': np.empty(0), 'z': np.empty(0)}  # Calibrated gyroscope data (°/s)
magRaw = {'x': np.empty(0), 'y': np.empty(0), 'z': np.empty(0)}  # Calibrated magnetometer data (µT)
timePoints = np.empty(0)  # Timestamps for gyro plots
startTime = QtCore.QTime.currentTime()  # Start time for elapsed time calculation# --- Serial Connection Initialization ---
try:
    ser = serial.Serial(serialPort, baudRate, timeout=timeout)  # Open serial port
    ser.reset_input_buffer()  # Clear input buffer to remove stale data
except serial.SerialException as e:
    msg = QtWidgets.QMessageBox()
    msg.setWindowTitle("Serial Error")
    msg.setText(f"Failed to open {serialPort}: {str(e)}\nCheck: 1) Port in Device Manager, 2) Close Arduino IDE Serial Monitor, 3) Run as admin")
    msg.exec_()
    exit(1)# --- Generate Arduino Code ---
# Strategy: Generate Arduino code with calibration parameters for onboard processing.
# Gyro offsets are in °/s to match Python processing.

def generateArduinoCode(to_file=False):
    code = [
        "void calibrateSensors() {",
        "    const float axOffset = " + str(accOffset['x']) + ";",
        "    const float ayOffset = " + str(accOffset['y']) + ";",
        "    const float azOffset = " + str(accOffset['z']) + ";",
        "    const float axScale = " + str(accScale['x']) + ";",
        "    const float ayScale = " + str(accScale['y']) + ";",
        "    const float azScale = " + str(accScale['z']) + ";",
        "    const float gxOffset = " + str(gxOffset) + ";",
        "    const float gyOffset = " + str(gyOffset) + ";",
        "    const float gzOffset = " + str(gzOffset) + ";",
        "    const float mxOffset = " + str(magOffset['x']) + ";",
        "    const float myOffset = " + str(magOffset['y']) + ";",
        "    const float mzOffset = " + str(magOffset['z']) + ";",
        "    const float mxScale = " + str(magScale['x']) + ";",
        "    const float myScale = " + str(magScale['y']) + ";",
        "    const float mzScale = " + str(magScale['z']) + ";",
        "",
        "    AxCal = (AxRaw - axOffset) * axScale;",
        "    AyCal = (AyRaw - ayOffset) * ayScale;",
        "    AzCal = (AzRaw - azOffset) * azScale;",
        "    GxCal = GxRaw*180/PI - gxOffset;",
        "    GyCal = GyRaw*180/PI - gyOffset;",
        "    GzCal = GzRaw*180/PI - gzOffset;",
        "    MxCal = (MxRaw - mxOffset) * mxScale;",
        "    MyCal = (MyRaw - myOffset) * myScale;",
        "    MzCal = (MzRaw - mzOffset) * mzScale;",
        "}"
    ]
    if to_file:
        try:
            file_path = os.path.join(os.getcwd(), 'calData.txt')
            with open(file_path, 'w', encoding='utf-8') as f:
                f.write("\n".join(code) + "\n")
            if os.path.exists(file_path) and os.path.getsize(file_path) > 0:
                with open(file_path, 'r', encoding='utf-8') as f:
                    if f.read().strip():
                        return True
                    raise Exception("File is empty")
            raise Exception("File was not created or is inaccessible")
        except Exception as e:
            msg = QtWidgets.QMessageBox()
            msg.setWindowTitle("File Write Error")
            msg.setText("Error writing calData.txt: " + str(e))
            msg.exec_()
            return False
    return True# --- Load Calibration Files ---
def loadCalibration():
    global gxOffset, gyOffset, gzOffset, accOffset, accScale, magOffset, magScale, plots, mag3DView
    loaded = []
    try:
        if os.path.exists('gCal.txt'):
            with open('gCal.txt', 'r') as f:
                values = list(map(float, f.readline().strip().split(',')))
                if len(values) == 3:
                    gxOffset, gyOffset, gzOffset = values  # Load gyro offsets (°/s)
                    loaded.append(f"Gyro (°/s): Gx={gxOffset:.6f}, Gy={gyOffset:.6f}, Gz={gzOffset:.6f}")
        if os.path.exists('accCal.txt'):
            with open('accCal.txt', 'r') as f:
                values = list(map(float, f.readline().strip().split(',')))
                if len(values) == 6:
                    accOffset['x'], accScale['x'], accOffset['y'], accScale['y'], accOffset['z'], accScale['z'] = values
                    for key in ['accXY', 'accYZ', 'accXZ']:
                        plots[key].setRange(xRange=(-1.2, 1.2), yRange=(-1.2, 1.2))  # ±1.2 m/s²
                    loaded.append(f"Acc (m/s²): Offsets x={accOffset['x']:.6f}, y={accOffset['y']:.6f}, z={accOffset['z']:.6f}, " +
                                 f"Scales x={accScale['x']:.6f}, y={accScale['y']:.6f}, z={accScale['z']:.6f}")
        if os.path.exists('magCal.txt'):
            with open('magCal.txt', 'r') as f:
                values = list(map(float, f.readline().strip().split(',')))
                if len(values) == 6:
                    magOffset['x'], magScale['x'], magOffset['y'], magScale['y'], magOffset['z'], magScale['z'] = values
                    for key in ['magXY', 'magYZ', 'magXZ']:
                        plots[key].setRange(xRange=(-1.2, 1.2), yRange=(-1.2, 1.2))  # ±1.2 µT
                    mag3DView.opts['distance'] = 3
                    mag3DView.setCameraPosition(distance=3, elevation=30, azimuth=45)
                    loaded.append(f"Mag (µT): Offsets x={magOffset['x']:.6f}, y={magOffset['y']:.6f}, z={magOffset['z']:.6f}, " +
                                 f"Scales x={magScale['x']:.6f}, y={magScale['y']:.6f}, z={magScale['z']:.6f}")
        if loaded:
            msg = QtWidgets.QMessageBox()
            msg.setWindowTitle("Calibration Loaded")
            msg.setText("Loaded calibration:\n" + "\n".join(loaded))
            msg.exec_()
            generateArduinoCode()
        else:
            msg = QtWidgets.QMessageBox()
            msg.setWindowTitle("No Calibration Found")
            msg.setText("No calibration files found. Please calibrate the sensors.")
            msg.exec_()
    except Exception as e:
        msg = QtWidgets.QMessageBox()
        msg.setWindowTitle("Calibration Load Error")
        msg.setText(f"Error loading calibration files: {str(e)}")
        msg.exec_()# --- Save Calibration ---
def saveCalibration():
    global gxOffset, gyOffset, gzOffset, accOffset, accScale, magOffset, magScale
    saved = []
    try:
        with open('gCal.txt', 'w') as f:
            f.write(f"{gxOffset},{gyOffset},{gzOffset}\n")
            saved.append(f"Gyro (°/s): Gx={gxOffset:.6f}, Gy={gyOffset:.6f}, Gz={gzOffset:.6f}")
        with open('accCal.txt', 'w') as f:
            f.write(f"{accOffset['x']},{accScale['x']},{accOffset['y']},{accScale['y']},{accOffset['z']},{accScale['z']}\n")
            saved.append(f"Acc (m/s²): Offsets x={accOffset['x']:.6f}, y={accOffset['y']:.6f}, z={accOffset['z']:.6f}, " +
                        f"Scales x={accScale['x']:.6f}, y={accScale['y']:.6f}, z={accScale['z']:.6f}")
        with open('magCal.txt', 'w') as f:
            f.write(f"{magOffset['x']},{magScale['x']},{magOffset['y']},{magScale['y']},{magOffset['z']},{magScale['z']}\n")
            saved.append(f"Mag (µT): Offsets x={magOffset['x']:.6f}, y={magOffset['y']:.6f}, z={magOffset['z']:.6f}, " +
                        f"Scales x={magScale['x']:.6f}, y={magScale['y']:.6f}, z={magScale['z']:.6f}")
        msg = QtWidgets.QMessageBox()
        msg.setWindowTitle("Calibration Saved")
        msg.setText("Saved calibration:\n" + "\n".join(saved))
        msg.exec_()
        generateArduinoCode()
    except Exception as e:
        msg = QtWidgets.QMessageBox()
        msg.setWindowTitle("Calibration Save Error")
        msg.setText(f"Error saving calibration files: {str(e)}")
        msg.exec_()# --- GUI Setup - Main Window ---
app = QtWidgets.QApplication([])
mainWindow = QtWidgets.QWidget()
mainWindow.setWindowTitle("9-Axis IMU Visualization (Acc/Mag: 1000 pts, Gyro: 100 pts)")
mainWindow.setMinimumSize(1000, 800)
mainLayout = QtWidgets.QVBoxLayout()
mainWindow.setLayout(mainLayout)
plotGrid = QtWidgets.QGridLayout()
plots = {}
scatterItems = {}
curveItems = {}
attitudeItems = {}
plotTitles = [
    ('accXY', 'Acc XY (m/s²)', 'X', 'Y', (255, 0, 0, 255)),  # Red
    ('accYZ', 'Acc YZ (m/s²)', 'Y', 'Z', (0, 255, 0, 255)),  # Green
    ('accXZ', 'Acc XZ (m/s²)', 'X', 'Z', (0, 0, 255, 255)),  # Blue
    ('magXY', 'Mag XY (µT)', 'X', 'Y', (0, 255, 255, 255)),  # Cyan
    ('magYZ', 'Mag YZ (µT)', 'Y', 'Z', (255, 0, 255, 255)),  # Magenta
    ('magXZ', 'Mag XZ (µT)', 'X', 'Z', (255, 255, 0, 255)),  # Yellow
    ('gyroX', 'Gyro X (°/s)', 'Time (s)', 'X', None),
    ('gyroY', 'Gyro Y (°/s)', 'Time (s)', 'Y', None),
    ('gyroZ', 'Gyro Z (°/s)', 'Time (s)', 'Z', None)
]
for idx, (key, title, xLabel, yLabel, color) in enumerate(plotTitles):
    plot = pg.PlotWidget(title=title)
    plot.setMinimumSize(200, 200)
    if 'acc' in key or 'mag' in key:
        plot.setAspectLocked(True)
        scatterItems[key] = pg.ScatterPlotItem(size=5, brush=pg.mkBrush(*color), pen=None)
        plot.addItem(scatterItems[key])
        if 'acc' in key:
            plot.setRange(xRange=(-10, 10), yRange=(-10, 10))  # ±10 m/s²
        if 'mag' in key:
            plot.setRange(xRange=(-1.2, 1.2), yRange=(-1.2, 1.2))  # ±1.2 µT
        plot.showGrid(x=True, y=True)
        plot.setLabel('bottom', xLabel)
        plot.setLabel('left', yLabel)
    elif 'gyro' in key:
        plot.showGrid(x=True, y=True)
        plot.setLabel('bottom', xLabel)
        plot.setLabel('left', yLabel)
        plot.setRange(yRange=(-5, 5))  # ±0.1 °/s for calibrated gyro
        curveItems[key] = plot.plot(pen=pg.mkPen('b', width=2))
    plotGrid.addWidget(plot, idx // 3, idx % 3)
    plots[key] = plot
mainLayout.addLayout(plotGrid)
buttonLayout = QtWidgets.QHBoxLayout()
calibrateGyroButton = QtWidgets.QPushButton("Calibrate Gyro")
calibrateGyroButton.setMinimumSize(200, 50)
calibrateGyroButton.setStyleSheet("background-color: #00FF00; color: black; font-size: 16px;")
calibrateAccButton = QtWidgets.QPushButton("Calibrate Accelerometer")
calibrateAccButton.setMinimumSize(200, 50)
calibrateAccButton.setStyleSheet("background-color: #FFFF00; color: black; font-size: 16px;")
calibrateMagButton = QtWidgets.QPushButton("Calibrate Magnetometer")
calibrateMagButton.setMinimumSize(200, 50)
calibrateMagButton.setStyleSheet("background-color: #FFFF00; color: black; font-size: 16px;")
saveCalButton = QtWidgets.QPushButton("Save Calibration")
saveCalButton.setMinimumSize(200, 50)
saveCalButton.setStyleSheet("background-color: #0000FF; color: white; font-size: 16px;")
generateCodeButton = QtWidgets.QPushButton("Generate Code")
generateCodeButton.setMinimumSize(200, 50)
generateCodeButton.setStyleSheet("background-color: #0000FF; color: white; font-size: 16px;")
stopButton = QtWidgets.QPushButton("Stop")
stopButton.setMinimumSize(200, 50)
stopButton.setStyleSheet("background-color: #FF0000; color: white; font-size: 16px;")
buttonLayout.addWidget(calibrateGyroButton)
buttonLayout.addWidget(calibrateAccButton)
buttonLayout.addWidget(calibrateMagButton)
buttonLayout.addWidget(saveCalButton)
buttonLayout.addWidget(generateCodeButton)
buttonLayout.addWidget(stopButton)
mainLayout.addLayout(buttonLayout)# --- 3D Magnetometer and Attitude Window ---
mag3DWindow = QtWidgets.QWidget()
mag3DWindow.setWindowTitle("3D Magnetic Field Vector and Attitude (µT, °)")
mag3DWindow.setMinimumSize(800, 800)
mag3DLayout = QtWidgets.QGridLayout()
mag3DWindow.setLayout(mag3DLayout)
mag3DView = GLViewWidget()
mag3DView.setCameraPosition(distance=3, elevation=30, azimuth=45)
mag3DLayout.addWidget(mag3DView, 0, 0)
sphereMesh = gl.MeshData.sphere(rows=20, cols=20, radius=1.0)
sphere = gl.GLMeshItem(meshdata=sphereMesh, smooth=True, color=(0.3, 0.3, 0.3, 0.2), shader='shaded', drawFaces=True)
mag3DView.addItem(sphere)
circleMesh = gl.MeshData.cylinder(rows=1, cols=50, radius=[1.0, 1.0], length=0.001)
xyCircle = gl.GLMeshItem(meshdata=circleMesh, smooth=True, color=(1, 0.5, 0, 0.4), shader='shaded', glOptions='additive')
xyCircle.rotate(90, 1, 0, 0)
xyCircle.setDepthValue(-5)
mag3DView.addItem(xyCircle)
for axis, color in zip([(1.2, 0, 0), (0, 1.2, 0), (0, 0, 1.2)], [(1, 0, 0, 1), (0, 1, 0, 1), (0, 0, 1, 1)]):
    line = gl.GLLinePlotItem(pos=np.array([[0, 0, 0], axis]), color=color, width=2, antialias=True)
    mag3DView.addItem(line)
vectorArrow = gl.GLLinePlotItem(pos=np.array([[0, 0, 0], [0, 0, 0]]), color=(1, 0, 0, 1), width=3, antialias=True)
vectorArrow.setDepthValue(10)
mag3DView.addItem(vectorArrow)
xyProjection = gl.GLLinePlotItem(pos=np.array([[0, 0, 0], [0, 0, 0]]), color=(0, 1, 1, 1), width=2, antialias=True)
xyProjection.setDepthValue(10)
mag3DView.addItem(xyProjection)
verticalComponent = gl.GLLinePlotItem(pos=np.array([[0, 0, 0], [0, 0, 0]]), color=(1, 0, 1, 1), width=2, antialias=True)
verticalComponent.setDepthValue(10)
mag3DView.addItem(verticalComponent)
vectorTrail = gl.GLLinePlotItem(pos=np.array([[0, 0, 0]]), color=(1, 1, 0, 0.6), width=1, antialias=True)
vectorTrail.setDepthValue(10)
mag3DView.addItem(vectorTrail)
attitudePlots = {}
attitudePlotTitles = [
    ('rollPlot', 'Roll (°)', '', ''),
    ('pitchPlot', 'Pitch (°)', '', ''),
    ('yawPlot', 'Yaw (°)', '', '')
]
for idx, (key, title, xLabel, yLabel) in enumerate(attitudePlotTitles):
    plot = pg.PlotWidget(title=title)
    plot.setMinimumSize(200, 200)
    plot.setRange(xRange=(-1.5, 1.5), yRange=(-1.5, 1.5))
    plot.setAspectLocked(True)
    plot.hideAxis('bottom')
    plot.hideAxis('left')
    readout = pg.TextItem("0.0°", anchor=(0.5, 0.5), color=(0, 255, 0))
    readout.setFont(QtGui.QFont("Courier New", 14, QtGui.QFont.Bold))
    if key in ['rollPlot', 'pitchPlot']:
        readout.setPos(0, -1.4)
    else:
        readout.setPos(0, -1.5)
    readout.setZValue(15)
    plot.addItem(readout)
    attitudeItems[f'{key}_readout'] = readout
    if key == 'rollPlot':
        skyX = np.array([-1.5, 1.5, 1.5, -1.5])
        skyY = np.array([0, 0, 1.5, 1.5])
        groundX = np.array([-1.5, 1.5, 1.5, -1.5])
        groundY = np.array([-1.5, -1.5, 0, 0])
        sky = pg.PlotDataItem(x=skyX, y=skyY, pen=None, fillLevel=1.5, brush=pg.mkBrush(0, 191, 255, 255))
        ground = pg.PlotDataItem(x=groundX, y=groundY, pen=None, fillLevel=-1.5, brush=pg.mkBrush(139, 69, 19, 255))
        plot.addItem(sky)
        plot.addItem(ground)
        horizon = pg.PlotDataItem(x=[-1, 1], y=[0, 0], pen=pg.mkPen(color=(0, 100, 0), width=3))
        plot.addItem(horizon)
        attitudeItems['roll_horizon'] = horizon
        for xPos, anchor in [(-1.2, (1, 0.5)), (1.2, (0, 0.5))]:
            text = pg.TextItem("0°", anchor=anchor, color=(255, 255, 0))
            text.setFont(QtGui.QFont("Arial", 12, QtGui.QFont.Bold))
            text.setPos(xPos, 0)
            text.setZValue(10)
            plot.addItem(text)
        for angle in [30, 60]:
            rad = math.radians(angle)
            sinRad = math.sin(rad)
            cosRad = math.cos(rad)
            text = pg.TextItem(f"{angle}°", anchor=(0, 0.5), color=(255, 255, 0))
            text.setFont(QtGui.QFont("Arial", 12, QtGui.QFont.Bold))
            text.setPos(1.2 * cosRad, 1.2 * sinRad)
            text.setZValue(10)
            plot.addItem(text)
            text = pg.TextItem(f"{angle}°", anchor=(1, 0.5), color=(255, 255, 0))
            text.setFont(QtGui.QFont("Arial", 12, QtGui.QFont.Bold))
            text.setPos(-1.2 * cosRad, 1.2 * sinRad)
            text.setZValue(10)
            plot.addItem(text)
            text = pg.TextItem(f"-{angle}°", anchor=(1, 0.5), color=(255, 255, 0))
            text.setFont(QtGui.QFont("Arial", 12, QtGui.QFont.Bold))
            text.setPos(-1.2 * cosRad, -1.2 * sinRad)
            text.setZValue(10)
            plot.addItem(text)
            text = pg.TextItem(f"-{angle}°", anchor=(0, 0.5), color=(255, 255, 0))
            text.setFont(QtGui.QFont("Arial", 12, QtGui.QFont.Bold))
            text.setPos(1.2 * cosRad, -1.2 * sinRad)
            text.setZValue(10)
            plot.addItem(text)
    elif key == 'pitchPlot':
        skyX = np.array([-1.5, 1.5, 1.5, -1.5])
        skyY = np.array([0, 0, 1.5, 1.5])
        groundX = np.array([-1.5, 1.5, 1.5, -1.5])
        groundY = np.array([-1.5, -1.5, 0, 0])
        sky = pg.PlotDataItem(x=skyX, y=skyY, pen=None, fillLevel=1.5, brush=pg.mkBrush(0, 191, 255, 255))
        ground = pg.PlotDataItem(x=groundX, y=groundY, pen=None, fillLevel=-1.5, brush=pg.mkBrush(139, 69, 19, 255))
        plot.addItem(sky)
        plot.addItem(ground)
        ladder = []
        for angle in [-90, -60, -30, -10, 0, 10, 30, 60, 90]:
            y = angle / 90 * 1.2
            if angle == 0:
                line = pg.PlotDataItem(x=[-1, 1], y=[y, y], pen=pg.mkPen(color=(0, 100, 0), width=3))
            else:
                line = pg.PlotDataItem(x=[-0.5, -0.2, -0.2, 0.2, 0.2, 0.5], y=[y, y, y+0.05, y+0.05, y, y], pen=pg.mkPen(color=(0, 100, 0), width=2))
                textLeft = pg.TextItem(f"{angle}°", anchor=(1, 0.5), color=(255, 255, 0))
                textLeft.setFont(QtGui.QFont("Arial", 12, QtGui.QFont.Bold))
                textLeft.setPos(-0.6, y)
                textRight = pg.TextItem(f"{angle}°", anchor=(0, 0.5), color=(255, 255, 0))
                textRight.setFont(QtGui.QFont("Arial", 12, QtGui.QFont.Bold))
                textRight.setPos(0.6, y)
                plot.addItem(textLeft)
                plot.addItem(textRight)
            plot.addItem(line)
            ladder.append(line)
        attitudeItems['pitch_ladder'] = ladder
    elif key == 'yawPlot':
        theta = np.linspace(0, 2 * np.pi, 100)
        xCircle = 1.2 * np.sin(theta)
        yCircle = 1.2 * np.cos(theta)
        circle = pg.PlotDataItem(x=xCircle, y=yCircle, pen=pg.mkPen('w', width=2), fillLevel=0, brush=pg.mkBrush(0, 0, 0, 255))
        plot.addItem(circle)
        for angle, label in [(0, 'N'), (90, 'E'), (180, 'S'), (270, 'W')]:
            rad = math.radians(angle)
            x = 1.3 * math.sin(rad)
            y = 1.3 * math.cos(rad)
            text = pg.TextItem(label, anchor=(0.5, 0.5), color=(255, 255, 0))
            text.setFont(QtGui.QFont("Arial", 12))
            text.setPos(x, y)
            plot.addItem(text)
        needle = pg.PlotDataItem(x=[0, 0], y=[0, 1], pen=pg.mkPen('r', width=3))
        plot.addItem(needle)
        attitudeItems['yaw_needle'] = needle
    if key == 'rollPlot':
        mag3DLayout.addWidget(plot, 0, 1)
    elif key == 'pitchPlot':
        mag3DLayout.addWidget(plot, 1, 0)
    elif key == 'yawPlot':
        mag3DLayout.addWidget(plot, 1, 1)
    attitudePlots[key] = plot# --- Calibrate Gyroscope ---
def calibrateGyro():
    global gxOffset, gyOffset, gzOffset
    msg = QtWidgets.QMessageBox()
    msg.setWindowTitle("Calibrate Gyro")
    msg.setText("Keep the device still for calibration. Press OK to start.")
    msg.exec_()
    gxSamples = []
    gySamples = []
    gzSamples = []
    sampleCount = 0
    ser.reset_input_buffer()
    while sampleCount < 200:
        if ser.in_waiting <= 0: continue
        try:
            line = ser.readline().decode('utf-8').strip()
            values = line.split(',')
            if len(values) != 9: continue
            ax, ay, az, gx, gy, gz, mx, my, mz = map(float, values)
            # Convert gyro data from rad/s to °/s
            gx = gx * 180.0 / math.pi
            gy = gy * 180.0 / math.pi
            gz = gz * 180.0 / math.pi
            gxSamples.append(gx)
            gySamples.append(gy)
            gzSamples.append(gz)
            sampleCount += 1
        except Exception:
            pass
        time.sleep(0.01)
    if not gxSamples: return
    gxOffset = np.mean(gxSamples)  # Offset in °/s
    gyOffset = np.mean(gySamples)  # Offset in °/s
    gzOffset = np.mean(gzSamples)  # Offset in °/s
    try:
        with open('gCal.txt', 'w') as f:
            f.write(f"{gxOffset},{gyOffset},{gzOffset}\n")
        msg = QtWidgets.QMessageBox()
        msg.setWindowTitle("Gyro Calibration Complete")
        msg.setText(f"Offsets (°/s): Gx={gxOffset:.6f}, Gy={gyOffset:.6f}, Gz={gzOffset:.6f}\nSaved to gCal.txt")
        msg.exec_()
        generateArduinoCode()
    except Exception as e:
        msg = QtWidgets.QMessageBox()
        msg.setWindowTitle("Gyro Calibration Error")
        msg.setText(f"Error saving gyro offsets: {str(e)}")
        msg.exec_()# --- Calibrate Accelerometer ---
def calibrateAcc():
    global accCalibrating, accMin, accMax, accOffset, accScale, accRaw, axSamples, aySamples, azSamples, plots
    if accCalibrating:
        calibrateAccButton.setText("Calibrate Accelerometer")
        accCalibrating = False
        if axSamples:
            accMin['x'] = min(axSamples)
            accMin['y'] = min(aySamples)
            accMin['z'] = min(azSamples)
            accMax['x'] = max(axSamples)
            accMax['y'] = max(aySamples)
            accMax['z'] = max(azSamples)
            accOffset['x'] = (accMin['x'] + accMax['x']) / 2.0
            accOffset['y'] = (accMin['y'] + accMax['y']) / 2.0
            accOffset['z'] = (accMin['z'] + accMax['z']) / 2.0
            rangeX = accMax['x'] - accMin['x']
            rangeY = accMax['y'] - accMin['y']
            rangeZ = accMax['z'] - accMin['z']
            avgRange = (rangeX + rangeY + rangeZ) / 3.0
            accScale['x'] = 2.0 / avgRange if avgRange != 0 else 1.0
            accScale['y'] = 2.0 / avgRange if avgRange != 0 else 1.0
            accScale['z'] = 2.0 / avgRange if avgRange != 0 else 1.0
            if avgRange < 0.5 or avgRange > 20.0:
                msg = QtWidgets.QMessageBox()
                msg.setWindowTitle("Calibration Warning")
                msg.setText(f"Average range {avgRange:.6f} is unusual.\nEnsure full 3D rotation during calibration.")
                msg.exec_()
            accRaw['x'] = np.empty(0)
            accRaw['y'] = np.empty(0)
            accRaw['z'] = np.empty(0)
            try:
                with open('accCal.txt', 'w') as f:
                    f.write(f"{accOffset['x']},{accScale['x']},{accOffset['y']},{accScale['y']},{accOffset['z']},{accScale['z']}\n")
                msg = QtWidgets.QMessageBox()
                msg.setWindowTitle("Acc Calibration Complete")
                msg.setText(f"Offsets (m/s²): Ax={accOffset['x']:.6f}, Ay={accOffset['y']:.6f}, Az={accOffset['z']:.6f}\n" +
                            f"Scales: Ax={accScale['x']:.6f}, Ay={accScale['y']:.6f}, Az={accScale['z']:.6f}\nSaved to accCal.txt")
                msg.exec_()
                generateArduinoCode()
            except Exception as e:
                msg = QtWidgets.QMessageBox()
                msg.setWindowTitle("Acc Calibration Error")
                msg.setText(f"Error saving acc offsets: {str(e)}")
                msg.exec_()
            for key in ['accXY', 'accYZ', 'accXZ']:
                plots[key].setRange(xRange=(-1.2, 1.2), yRange=(-1.2, 1.2))
        return
    accCalibrating = True
    accMin = {'x': float('inf'), 'y': float('inf'), 'z': float('inf')}
    accMax = {'x': float('-inf'), 'y': float('-inf'), 'z': float('-inf')}
    axSamples = []
    aySamples = []
    azSamples = []
    accRaw['x'] = np.empty(0)
    accRaw['y'] = np.empty(0)
    accRaw['z'] = np.empty(0)
    calibrateAccButton.setText("Stop Acc Calibration")
    msg = QtWidgets.QMessageBox()
    msg.setWindowTitle("Accelerometer Calibration")
    msg.setText("Rotate device in all directions (full 3D rotation) to capture min/max values for all axes.")
    msg.exec_()# --- Calibrate Magnetometer ---
def calibrateMag():
    global magCalibrating, magMin, magMax, magOffset, magScale, magRaw, mxSamples, mySamples, mzSamples, magRawMin, magRawMax, plots, mag3DView, vectorArrow, vectorTrail, xyProjection, verticalComponent, trailBuffer
    if magCalibrating:
        calibrateMagButton.setText("Calibrate Magnetometer")
        magCalibrating = False
        if mxSamples:
            magMin['x'] = min(mxSamples)
            magMin['y'] = min(mySamples)
            magMin['z'] = min(mzSamples)
            magMax['x'] = max(mxSamples)
            magMax['y'] = max(mySamples)
            magMax['z'] = max(mzSamples)
            
            # --- CENTER OFFSET (unchanged) ---
            magOffset['x'] = (magMin['x'] + magMax['x']) / 2.0
            magOffset['y'] = (magMin['y'] + magMax['y']) / 2.0
            magOffset['z'] = (magMin['z'] + magMax['z']) / 2.0

            # --- PER-AXIS SCALING TO ±1.0 (NEW) ---
            rangeX = magMax['x'] - magMin['x']
            rangeY = magMax['y'] - magMin['y']
            rangeZ = magMax['z'] - magMin['z']

            magScale['x'] = 2.0 / rangeX if rangeX > 1e-6 else 1.0
            magScale['y'] = 2.0 / rangeY if rangeY > 1e-6 else 1.0
            magScale['z'] = 2.0 / rangeZ if rangeZ > 1e-6 else 1.0

            # Clear buffers
            magRaw['x'] = np.empty(0)
            magRaw['y'] = np.empty(0)
            magRaw['z'] = np.empty(0)
            magRawMin = {'x': float('inf'), 'y': float('inf'), 'z': float('inf')}
            magRawMax = {'x': float('-inf'), 'y': float('-inf'), 'z': float('-inf')}
            trailBuffer = []
            vectorArrow.setData(pos=np.array([[0, 0, 0], [0, 0, 0]]))
            vectorTrail.setData(pos=np.array([[0, 0, 0]]))
            xyProjection.setData(pos=np.array([[0, 0, 0], [0, 0, 0]]))
            verticalComponent.setData(pos=np.array([[0, 0, 0], [0, 0, 0]]))

            try:
                with open('magCal.txt', 'w') as f:
                    f.write(f"{magOffset['x']},{magScale['x']},{magOffset['y']},{magScale['y']},{magOffset['z']},{magScale['z']}\n")
                msg = QtWidgets.QMessageBox()
                msg.setWindowTitle("Mag Calibration Complete")
                msg.setText(
                    f"Offsets (arb. units): Mx={magOffset['x']:.6f}, My={magOffset['y']:.6f}, Mz={magOffset['z']:.6f}\n"
                    f"Scales (per-axis to ±1): X={magScale['x']:.6f}, Y={magScale['y']:.6f}, Z={magScale['z']:.6f}\n"
                    f"Saved to magCal.txt\n"
                    f"Your XZ circle will now be perfectly round from -1 to +1"
                )
                msg.exec_()
                generateArduinoCode()
            except Exception as e:
                msg = QtWidgets.QMessageBox()
                msg.setWindowTitle("Mag Calibration Error")
                msg.setText(f"Error saving mag offsets: {str(e)}")
                msg.exec_()

            for key in ['magXY', 'magYZ', 'magXZ']:
                plots[key].setRange(xRange=(-1.2, 1.2), yRange=(-1.2, 1.2))
            mag3DView.opts['distance'] = 3
            mag3DView.setCameraPosition(distance=3, elevation=30, azimuth=45)
        return

    # --- Start Calibration ---
    magCalibrating = True
    magMin = {'x': float('inf'), 'y': float('inf'), 'z': float('inf')}
    magMax = {'x': float('-inf'), 'y': float('-inf'), 'z': float('-inf')}
    mxSamples = []
    mySamples = []
    mzSamples = []
    magRaw['x'] = np.empty(0)
    magRaw['y'] = np.empty(0)
    magRaw['z'] = np.empty(0)
    magRawMin = {'x': float('inf'), 'y': float('inf'), 'z': float('inf')}
    magRawMax = {'x': float('-inf'), 'y': float('-inf'), 'z': float('-inf')}
    trailBuffer = []
    vectorArrow.setData(pos=np.array([[0, 0, 0], [0, 0, 0]]))
    vectorTrail.setData(pos=np.array([[0, 0, 0]]))
    xyProjection.setData(pos=np.array([[0, 0, 0], [0, 0, 0]]))
    verticalComponent.setData(pos=np.array([[0, 0, 0], [0, 0, 0]]))
    calibrateMagButton.setText("Stop Mag Calibration")
    msg = QtWidgets.QMessageBox()
    msg.setWindowTitle("Magnetometer Calibration")
    msg.setText("Rotate device in figure-8 pattern to capture min/max values for all axes.\n"
                "After calibration, XZ circle will be forced to ±1.0")
    msg.exec_()
def generateCode():
    success = generateArduinoCode(to_file=True)
    msg = QtWidgets.QMessageBox()
    msg.setWindowTitle("Generate Code")
    if success:
        msg.setText("Arduino calibration function saved to calData.txt")
    else:
        msg.setText("Error saving calData.txt.")
    msg.exec_()# --- Stop Program ---
def stopProgram():
    try:
        plotTimer.stop()
        if ser.is_open:
            ser.close()
        mainWindow.close()
        mag3DWindow.close()
        app.exit(0)
    except Exception as e:
        msg = QtWidgets.QMessageBox()
        msg.setWindowTitle("Stop Error")
        msg.setText(f"Error stopping program: {str(e)}")
        msg.exec_()# --- Update Plots ---
def updatePlots():
    global accRaw, gyroRaw, magRaw, timePoints, gxOffset, gyOffset, gzOffset
    global accCalibrating, magCalibrating, accMin, accMax, magMin, magMax
    global accOffset, accScale, magOffset, magScale, accFiltered, magFiltered
    global axSamples, aySamples, azSamples, mxSamples, mySamples, mzSamples
    global magRawMin, magRawMax, vectorArrow, vectorTrail, xyProjection, verticalComponent, trailBuffer
    global attitudeItems, attitudePlots
    if ser.in_waiting <= 0: return
    try:
        line = ser.readline().decode('utf-8').strip()
        values = line.split(',')
        if len(values) != 9: return
        ax, ay, az, gx, gy, gz, mx, my, mz = map(float, values)
        # Convert gyro data from rad/s to °/s
        gx = gx * 180.0 / math.pi
        gy = gy * 180.0 / math.pi
        gz = gz * 180.0 / math.pi
        # Apply low-pass filter to accelerometer data
        accFiltered['x'] = alpha * ax + (1 - alpha) * accFiltered['x'] if accFiltered['x'] is not None else ax
        accFiltered['y'] = alpha * ay + (1 - alpha) * accFiltered['y'] if accFiltered['y'] is not None else ay
        accFiltered['z'] = alpha * az + (1 - alpha) * accFiltered['z'] if accFiltered['z'] is not None else az
        ax = accFiltered['x']  # m/s²
        ay = accFiltered['y']
        az = accFiltered['z']
        # Apply low-pass filter to magnetometer data
        magFiltered['x'] = alpha * mx + (1 - alpha) * magFiltered['x'] if magFiltered['x'] is not None else mx
        magFiltered['y'] = alpha * my + (1 - alpha) * magFiltered['y'] if magFiltered['y'] is not None else my
        magFiltered['z'] = alpha * mz + (1 - alpha) * magFiltered['z'] if magFiltered['z'] is not None else mz
        mx = magFiltered['x']  # QMC5883L arbitrary units
        my = magFiltered['y']
        mz = magFiltered['z']
        # Collect samples during calibration
        if accCalibrating:
            axSamples.append(ax)
            aySamples.append(ay)
            azSamples.append(az)
            accMin['x'] = min(accMin['x'], ax)
            accMin['y'] = min(accMin['y'], ay)
            accMin['z'] = min(accMin['z'], az)
            accMax['x'] = max(accMax['x'], ax)
            accMax['y'] = max(accMax['y'], ay)
            accMax['z'] = max(accMax['z'], az)
        if magCalibrating:
            mxSamples.append(mx)
            mySamples.append(my)
            mzSamples.append(mz)
            magMin['x'] = min(magMin['x'], mx)
            magMin['y'] = min(magMin['y'], my)
            magMin['z'] = min(magMin['z'], mz)
            magMax['x'] = max(magMax['x'], mx)
            magMax['y'] = max(magMax['y'], my)
            magMax['z'] = max(magMax['z'], mz)
        # Apply calibration
        axCal = (ax - accOffset['x']) * accScale['x']  # m/s²
        ayCal = (ay - accOffset['y']) * accScale['y']
        azCal = (az - accOffset['z']) * accScale['z']
        gxCal = gx - gxOffset  # °/s
        gyCal = gy - gyOffset
        gzCal = gz - gzOffset
        mxCal = (mx - magOffset['x']) * magScale['x']  # µT
        myCal = (my - magOffset['y']) * magScale['y']
        mzCal = (mz - magOffset['z']) * magScale['z']
        # Determine accelerometer data to plot
        if accCalibrating:
            ax_plot = ax
            ay_plot = ay
            az_plot = az
        else:
            ax_plot = axCal
            ay_plot = ayCal
            az_plot = azCal
        # Determine magnetometer data to plot
        if magCalibrating:
            mx_plot = mx
            my_plot = my
            mz_plot = mz
        else:
            mx_plot = mxCal
            my_plot = myCal
            mz_plot = mzCal
        # Calculate roll and pitch from accelerometer (NED: x north, y east, z down)
        roll = math.atan2(ayCal, azCal + epsilon) * 180 / math.pi  # °
        pitch = math.atan2(-axCal, math.sqrt(ayCal**2 + azCal**2 + epsilon)) * 180 / math.pi  # °
        phi = math.radians(roll)
        theta = math.radians(pitch)
        # Compute tilt-compensated yaw
        mxH = mxCal * math.cos(theta) + myCal * math.sin(phi) * math.sin(theta) + mzCal * math.cos(phi) * math.sin(theta)
        myH = myCal * math.cos(phi) - mzCal * math.sin(phi)
        yaw = math.atan2(myH, mxH + epsilon) * 180 / math.pi
        if yaw < 0:
            yaw += 360  # Normalize to 0-360°
        # Update attitude readouts
        attitudeItems['rollPlot_readout'].setText(f"Roll: {-roll:+.1f}°")
        attitudeItems['pitchPlot_readout'].setText(f"Pitch: {-pitch:+.1f}°")
        attitudeItems['yawPlot_readout'].setText(f"Yaw: {yaw:.1f}°")        # Update 3D magnetic vector visualization
        vec = np.array([mx_plot, my_plot, mz_plot])
        norm = np.linalg.norm(vec)
        if norm > epsilon:
            unitVec = vec / norm
            vectorArrow.setData(pos=np.array([[0, 0, 0], unitVec]), color=(1, 0, 0, 1), width=3)
            xyProj = np.array([unitVec[0], unitVec[1], 0])
            xyProjection.setData(pos=np.array([[0, 0, 0], xyProj]), color=(0, 1, 1, 1), width=2)
            verticalComponent.setData(pos=np.array([xyProj, unitVec]), color=(1, 0, 1, 1), width=2)
            trailBuffer.append(unitVec)
            trailBuffer = trailBuffer[-trailMaxPoints:]
            vectorTrail.setData(pos=np.array(trailBuffer), color=(1, 1, 0, 0.6), width=1)
        # Update plot ranges for accelerometer if in raw mode
        if accCalibrating or (accScale['x'] == 1.0 and accOffset['x'] == 0.0):
            accRawMin = {'x': min(accRaw['x'], default=ax_plot) if len(accRaw['x']) > 0 else ax_plot,
                         'y': min(accRaw['y'], default=ay_plot) if len(accRaw['y']) > 0 else ay_plot,
                         'z': min(accRaw['z'], default=az_plot) if len(accRaw['z']) > 0 else az_plot}
            accRawMax = {'x': max(accRaw['x'], default=ax_plot) if len(accRaw['x']) > 0 else ax_plot,
                         'y': max(accRaw['y'], default=ay_plot) if len(accRaw['y']) > 0 else ay_plot,
                         'z': max(accRaw['z'], default=az_plot) if len(accRaw['z']) > 0 else az_plot}
            xMin = accRawMin['x'] * 1.1
            xMax = accRawMax['x'] * 1.1
            yMin = accRawMin['y'] * 1.1
            yMax = accRawMax['y'] * 1.1
            zMin = accRawMin['z'] * 1.1
            zMax = accRawMax['z'] * 1.1
            plots['accXY'].setRange(xRange=(xMin, xMax), yRange=(yMin, yMax))
            plots['accYZ'].setRange(xRange=(yMin, yMax), yRange=(zMin, zMax))
            plots['accXZ'].setRange(xRange=(xMin, xMax), yRange=(zMin, zMax))
        # Update plot ranges for magnetometer if in raw mode
        use_raw_mag_range = magCalibrating or (magScale['x'] == 1.0 and magOffset['x'] == 0.0)
        if use_raw_mag_range:
            magRawMin['x'] = min(magRawMin['x'], mx)
            magRawMax['x'] = max(magRawMax['x'], mx)
            magRawMin['y'] = min(magRawMin['y'], my)
            magRawMax['y'] = max(magRawMax['y'], my)
            magRawMin['z'] = min(magRawMin['z'], mz)
            magRawMax['z'] = max(magRawMax['z'], mz)
            xMin = magRawMin['x'] * 1.1
            xMax = magRawMax['x'] * 1.1
            yMin = magRawMin['y'] * 1.1
            yMax = magRawMax['y'] * 1.1
            zMin = magRawMin['z'] * 1.1
            zMax = magRawMax['z'] * 1.1
            mag3DView.opts['distance'] = max(xMax - xMin, yMax - yMin, zMax - zMin) * 1.5
            mag3DView.setCameraPosition(distance=mag3DView.opts['distance'])
            plots['magXY'].setRange(xRange=(xMin, xMax), yRange=(yMin, yMax))
            plots['magYZ'].setRange(xRange=(yMin, yMax), yRange=(zMin, zMax))
            plots['magXZ'].setRange(xRange=(xMin, xMax), yRange=(zMin, zMax))
        # Store data
        accRaw['x'] = np.append(accRaw['x'], ax_plot)[-accMagMaxPoints:]
        accRaw['y'] = np.append(accRaw['y'], ay_plot)[-accMagMaxPoints:]
        accRaw['z'] = np.append(accRaw['z'], az_plot)[-accMagMaxPoints:]
        gyroRaw['x'] = np.append(gyroRaw['x'], gxCal)[-gyroMaxPoints:]
        gyroRaw['y'] = np.append(gyroRaw['y'], gyCal)[-gyroMaxPoints:]
        gyroRaw['z'] = np.append(gyroRaw['z'], gzCal)[-gyroMaxPoints:]
        magRaw['x'] = np.append(magRaw['x'], mx_plot)[-accMagMaxPoints:]
        magRaw['y'] = np.append(magRaw['y'], my_plot)[-accMagMaxPoints:]
        magRaw['z'] = np.append(magRaw['z'], mz_plot)[-accMagMaxPoints:]
        elapsed = startTime.msecsTo(QtCore.QTime.currentTime()) / 1000.0
        timePoints = np.append(timePoints, elapsed)[-gyroMaxPoints:]
        # Update 2D scatter plots
        scatterItems['accXY'].setData(x=accRaw['x'], y=accRaw['y'])
        scatterItems['accYZ'].setData(x=accRaw['y'], y=accRaw['z'])
        scatterItems['accXZ'].setData(x=accRaw['x'], y=accRaw['z'])
        scatterItems['magXY'].setData(x=magRaw['x'], y=magRaw['y'])
        scatterItems['magYZ'].setData(x=magRaw['y'], y=magRaw['z'])
        scatterItems['magXZ'].setData(x=magRaw['x'], y=magRaw['z'])
        if len(timePoints) <= 0: return
        xMin = max(0, timePoints[-1] - gyroTimeWindow)
        xMax = timePoints[-1]
        for key in ['gyroX', 'gyroY', 'gyroZ']:
            plots[key].setRange(xRange=(xMin, xMax))
            curveItems[key].setData(x=timePoints, y=gyroRaw[key[-1].lower()])
        # Update roll horizon
        rollRad = math.radians(roll)
        x1 = -1 * math.cos(rollRad)
        y1 = 1 * math.sin(rollRad)
        x2 = 1 * math.cos(rollRad)
        y2 = -1 * math.sin(rollRad)
        attitudeItems['roll_horizon'].setData(x=[x1, x2], y=[y1, y2])
        # Update pitch ladder
        pitchOffset = -pitch / 90 * 1.2
        for idx, angle in enumerate([-90, -60, -30, -10, 0, 10, 30, 60, 90]):
            yBase = angle / 90 * 1.2
            yShifted = yBase + pitchOffset
            if angle == 0:
                attitudeItems['pitch_ladder'][idx].setData(x=[-1, 1], y=[yShifted, yShifted])
            else:
                attitudeItems['pitch_ladder'][idx].setData(x=[-0.5, -0.2, -0.2, 0.2, 0.2, 0.5], y=[yShifted, yShifted, yShifted+0.05, yShifted+0.05, yShifted, yShifted])
        # Update yaw needle
        yawRad = math.radians(yaw)
        needleX = 1 * math.sin(yawRad)
        needleY = 1 * math.cos(yawRad)
        attitudeItems['yaw_needle'].setData(x=[0, needleX], y=[0, needleY])
    except Exception:
        pass# --- Connect Buttons and Start Application ---
calibrateGyroButton.clicked.connect(calibrateGyro)
calibrateAccButton.clicked.connect(calibrateAcc)
calibrateMagButton.clicked.connect(calibrateMag)
saveCalButton.clicked.connect(saveCalibration)
generateCodeButton.clicked.connect(generateCode)
stopButton.clicked.connect(stopProgram)
ser.reset_input_buffer()
loadCalibration()
plotTimer = QtCore.QTimer()
plotTimer.timeout.connect(updatePlots)
plotTimer.start(50)
mainWindow.show()
mag3DWindow.show()
try:
    app.exec_()
except Exception as e:
    msg = QtWidgets.QMessageBox()
    msg.setWindowTitle("Application Error")
    msg.setText(f"Application error: {str(e)}")
    msg.exec_()
finally:
    if ser.is_open:
        ser.close()

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import serial

import numpy as np

from PyQt5 import QtWidgets, QtCore, QtGui

import pyqtgraph as pg

import pyqtgraph.opengl as gl

from pyqtgraph.opengl import GLViewWidget, GLLinePlotItem, GLMeshItem

import time

import os

import math# --- Serial Port Configuration ---

# Strategy: Set up serial communication with the IMU to receive raw sensor data:

# ax, ay, az (m/s²), gx, gy, gz (rad/s), mx, my, mz (arbitrary units from QMC5883L).

# Convert gyro data to °/s immediately after reading for consistency with plots and calibration.

serialPort = 'COM8' # Serial port for IMU communication (adjust as needed)

baudRate = 115200 # Baud rate matching IMU configuration

timeout = 0.1 # Serial read timeout in seconds

accMagMaxPoints = 1000 # Max points for accelerometer/magnetometer plots

gyroMaxPoints = 100 # Max points for gyroscope plots

trailMaxPoints = 100 # Max points for 3D magnetic trail

gyroTimeWindow = 5.0 # Time window for gyro plots in seconds

alpha = 0.3 # Low-pass filter constant for smoothing accelerometer/magnetometer data

epsilon = 1e-6 # Small constant to prevent division by zero in calculations# --- Calibration Variables ---

# Strategy: Store calibration parameters to correct sensor biases and scales.

# Gyro offsets are in °/s (converted from rad/s on input).

# Accelerometer in m/s², magnetometer in µT after calibration.

gxOffset = 0.0 # Gyroscope x-axis offset (°/s)

gyOffset = 0.0 # Gyroscope y-axis offset (°/s)

gzOffset = 0.0 # Gyroscope z-axis offset (°/s)

accCalibrating = False # Flag for accelerometer calibration mode

magCalibrating = False # Flag for magnetometer calibration mode

accMin = {'x': float('inf'), 'y': float('inf'), 'z': float('inf')} # Min accelerometer readings (m/s²)

accMax = {'x': float('-inf'), 'y': float('-inf'), 'z': float('-inf')} # Max accelerometer readings (m/s²)

magMin = {'x': float('inf'), 'y': float('inf'), 'z': float('inf')} # Min magnetometer readings (arb. units)

magMax = {'x': float('-inf'), 'y': float('-inf'), 'z': float('-inf')} # Max magnetometer readings (arb. units)

magRawMin = {'x': float('inf'), 'y': float('inf'), 'z': float('inf')} # Min raw magnetometer readings

magRawMax = {'x': float('-inf'), 'y': float('-inf'), 'z': float('-inf')} # Max raw magnetometer readings

accOffset = {'x': 0.0, 'y': 0.0, 'z': 0.0} # Accelerometer offsets (m/s²)

accScale = {'x': 1.0, 'y': 1.0, 'z': 1.0} # Accelerometer scales

magOffset = {'x': 0.0, 'y': 0.0, 'z': 0.0} # Magnetometer offsets (arb. units)

magScale = {'x': 1.0, 'y': 1.0, 'z': 1.0} # Magnetometer scales (to µT)

accFiltered = {'x': None, 'y': None, 'z': None} # Filtered accelerometer data (m/s²)

magFiltered = {'x': None, 'y': None, 'z': None} # Filtered magnetometer data (arb. units)

axSamples = [] # Accelerometer x-axis samples during calibration

aySamples = [] # Accelerometer y-axis samples during calibration

azSamples = [] # Accelerometer z-axis samples during calibration

mxSamples = [] # Magnetometer x-axis samples during calibration

mySamples = [] # Magnetometer y-axis samples during calibration

mzSamples = [] # Magnetometer z-axis samples during calibration

trailBuffer = [] # Buffer for 3D magnetic vector trail# --- Data Storage ---

# Strategy: Store raw and calibrated sensor data in numpy arrays for efficient plotting.

# Gyro data is stored in °/s after conversion from rad/s.

accRaw = {'x': np.empty(0), 'y': np.empty(0), 'z': np.empty(0)} # Raw accelerometer data (m/s²)

gyroRaw = {'x': np.empty(0), 'y': np.empty(0), 'z': np.empty(0)} # Calibrated gyroscope data (°/s)

magRaw = {'x': np.empty(0), 'y': np.empty(0), 'z': np.empty(0)} # Calibrated magnetometer data (µT)

timePoints = np.empty(0) # Timestamps for gyro plots

startTime = QtCore.QTime.currentTime() # Start time for elapsed time calculation# --- Serial Connection Initialization ---

try:

ser = serial.Serial(serialPort, baudRate, timeout=timeout) # Open serial port

ser.reset_input_buffer() # Clear input buffer to remove stale data

except serial.SerialException as e:

msg = QtWidgets.QMessageBox()

msg.setWindowTitle("Serial Error")

msg.setText(f"Failed to open {serialPort}: {str(e)}\nCheck: 1) Port in Device Manager, 2) Close Arduino IDE Serial Monitor, 3) Run as admin")

msg.exec_()

exit(1)# --- Generate Arduino Code ---

# Strategy: Generate Arduino code with calibration parameters for onboard processing.

# Gyro offsets are in °/s to match Python processing.

def generateArduinoCode(to_file=False):

code = [

"void calibrateSensors() {",

" const float axOffset = " + str(accOffset['x']) + ";",

" const float ayOffset = " + str(accOffset['y']) + ";",

" const float azOffset = " + str(accOffset['z']) + ";",

" const float axScale = " + str(accScale['x']) + ";",

" const float ayScale = " + str(accScale['y']) + ";",

" const float azScale = " + str(accScale['z']) + ";",

" const float gxOffset = " + str(gxOffset) + ";",

" const float gyOffset = " + str(gyOffset) + ";",

" const float gzOffset = " + str(gzOffset) + ";",

" const float mxOffset = " + str(magOffset['x']) + ";",

" const float myOffset = " + str(magOffset['y']) + ";",

" const float mzOffset = " + str(magOffset['z']) + ";",

" const float mxScale = " + str(magScale['x']) + ";",

" const float myScale = " + str(magScale['y']) + ";",

" const float mzScale = " + str(magScale['z']) + ";",

"",

" AxCal = (AxRaw - axOffset) * axScale;",

" AyCal = (AyRaw - ayOffset) * ayScale;",

" AzCal = (AzRaw - azOffset) * azScale;",

" GxCal = GxRaw*180/PI - gxOffset;",

" GyCal = GyRaw*180/PI - gyOffset;",

" GzCal = GzRaw*180/PI - gzOffset;",

" MxCal = (MxRaw - mxOffset) * mxScale;",

" MyCal = (MyRaw - myOffset) * myScale;",

" MzCal = (MzRaw - mzOffset) * mzScale;",

"}"

]

if to_file:

try:

file_path = os.path.join(os.getcwd(), 'calData.txt')

with open(file_path, 'w', encoding='utf-8') as f:

f.write("\n".join(code) + "\n")

if os.path.exists(file_path) and os.path.getsize(file_path) > 0:

with open(file_path, 'r', encoding='utf-8') as f:

if f.read().strip():

return True

raise Exception("File is empty")

raise Exception("File was not created or is inaccessible")

except Exception as e:

msg = QtWidgets.QMessageBox()

msg.setWindowTitle("File Write Error")

msg.setText("Error writing calData.txt: " + str(e))

msg.exec_()

return False

return True# --- Load Calibration Files ---

def loadCalibration():

global gxOffset, gyOffset, gzOffset, accOffset, accScale, magOffset, magScale, plots, mag3DView

loaded = []

try:

if os.path.exists('gCal.txt'):

with open('gCal.txt', 'r') as f:

values = list(map(float, f.readline().strip().split(',')))

if len(values) == 3:

gxOffset, gyOffset, gzOffset = values # Load gyro offsets (°/s)

loaded.append(f"Gyro (°/s): Gx={gxOffset:.6f}, Gy={gyOffset:.6f}, Gz={gzOffset:.6f}")

if os.path.exists('accCal.txt'):

with open('accCal.txt', 'r') as f:

values = list(map(float, f.readline().strip().split(',')))

if len(values) == 6:

accOffset['x'], accScale['x'], accOffset['y'], accScale['y'], accOffset['z'], accScale['z'] = values

for key in ['accXY', 'accYZ', 'accXZ']:

plots[key].setRange(xRange=(-1.2, 1.2), yRange=(-1.2, 1.2)) # ±1.2 m/s²

loaded.append(f"Acc (m/s²): Offsets x={accOffset['x']:.6f}, y={accOffset['y']:.6f}, z={accOffset['z']:.6f}, " +

f"Scales x={accScale['x']:.6f}, y={accScale['y']:.6f}, z={accScale['z']:.6f}")

if os.path.exists('magCal.txt'):

with open('magCal.txt', 'r') as f:

values = list(map(float, f.readline().strip().split(',')))

if len(values) == 6:

magOffset['x'], magScale['x'], magOffset['y'], magScale['y'], magOffset['z'], magScale['z'] = values

for key in ['magXY', 'magYZ', 'magXZ']:

plots[key].setRange(xRange=(-1.2, 1.2), yRange=(-1.2, 1.2)) # ±1.2 µT

mag3DView.opts['distance'] = 3

mag3DView.setCameraPosition(distance=3, elevation=30, azimuth=45)

loaded.append(f"Mag (µT): Offsets x={magOffset['x']:.6f}, y={magOffset['y']:.6f}, z={magOffset['z']:.6f}, " +

f"Scales x={magScale['x']:.6f}, y={magScale['y']:.6f}, z={magScale['z']:.6f}")

if loaded:

msg = QtWidgets.QMessageBox()

msg.setWindowTitle("Calibration Loaded")

msg.setText("Loaded calibration:\n" + "\n".join(loaded))

msg.exec_()

generateArduinoCode()

else:

msg = QtWidgets.QMessageBox()

msg.setWindowTitle("No Calibration Found")

msg.setText("No calibration files found. Please calibrate the sensors.")

msg.exec_()

except Exception as e:

msg = QtWidgets.QMessageBox()

msg.setWindowTitle("Calibration Load Error")

msg.setText(f"Error loading calibration files: {str(e)}")

msg.exec_()# --- Save Calibration ---

def saveCalibration():

global gxOffset, gyOffset, gzOffset, accOffset, accScale, magOffset, magScale

saved = []

try:

with open('gCal.txt', 'w') as f:

f.write(f"{gxOffset},{gyOffset},{gzOffset}\n")

saved.append(f"Gyro (°/s): Gx={gxOffset:.6f}, Gy={gyOffset:.6f}, Gz={gzOffset:.6f}")

with open('accCal.txt', 'w') as f:

f.write(f"{accOffset['x']},{accScale['x']},{accOffset['y']},{accScale['y']},{accOffset['z']},{accScale['z']}\n")

saved.append(f"Acc (m/s²): Offsets x={accOffset['x']:.6f}, y={accOffset['y']:.6f}, z={accOffset['z']:.6f}, " +

f"Scales x={accScale['x']:.6f}, y={accScale['y']:.6f}, z={accScale['z']:.6f}")

with open('magCal.txt', 'w') as f:

f.write(f"{magOffset['x']},{magScale['x']},{magOffset['y']},{magScale['y']},{magOffset['z']},{magScale['z']}\n")

saved.append(f"Mag (µT): Offsets x={magOffset['x']:.6f}, y={magOffset['y']:.6f}, z={magOffset['z']:.6f}, " +

f"Scales x={magScale['x']:.6f}, y={magScale['y']:.6f}, z={magScale['z']:.6f}")

msg = QtWidgets.QMessageBox()

msg.setWindowTitle("Calibration Saved")

msg.setText("Saved calibration:\n" + "\n".join(saved))

msg.exec_()

generateArduinoCode()

except Exception as e:

msg = QtWidgets.QMessageBox()

msg.setWindowTitle("Calibration Save Error")

msg.setText(f"Error saving calibration files: {str(e)}")

msg.exec_()# --- GUI Setup - Main Window ---

app = QtWidgets.QApplication([])

mainWindow = QtWidgets.QWidget()

mainWindow.setWindowTitle("9-Axis IMU Visualization (Acc/Mag: 1000 pts, Gyro: 100 pts)")

mainWindow.setMinimumSize(1000, 800)

mainLayout = QtWidgets.QVBoxLayout()

mainWindow.setLayout(mainLayout)

plotGrid = QtWidgets.QGridLayout()

plots = {}

scatterItems = {}

curveItems = {}

attitudeItems = {}

plotTitles = [

('accXY', 'Acc XY (m/s²)', 'X', 'Y', (255, 0, 0, 255)), # Red

('accYZ', 'Acc YZ (m/s²)', 'Y', 'Z', (0, 255, 0, 255)), # Green

('accXZ', 'Acc XZ (m/s²)', 'X', 'Z', (0, 0, 255, 255)), # Blue

('magXY', 'Mag XY (µT)', 'X', 'Y', (0, 255, 255, 255)), # Cyan

('magYZ', 'Mag YZ (µT)', 'Y', 'Z', (255, 0, 255, 255)), # Magenta

('magXZ', 'Mag XZ (µT)', 'X', 'Z', (255, 255, 0, 255)), # Yellow

('gyroX', 'Gyro X (°/s)', 'Time (s)', 'X', None),

('gyroY', 'Gyro Y (°/s)', 'Time (s)', 'Y', None),

('gyroZ', 'Gyro Z (°/s)', 'Time (s)', 'Z', None)

]

for idx, (key, title, xLabel, yLabel, color) in enumerate(plotTitles):

plot = pg.PlotWidget(title=title)

plot.setMinimumSize(200, 200)

if 'acc' in key or 'mag' in key:

plot.setAspectLocked(True)

scatterItems[key] = pg.ScatterPlotItem(size=5, brush=pg.mkBrush(*color), pen=None)

plot.addItem(scatterItems[key])

if 'acc' in key:

plot.setRange(xRange=(-10, 10), yRange=(-10, 10)) # ±10 m/s²

if 'mag' in key:

plot.setRange(xRange=(-1.2, 1.2), yRange=(-1.2, 1.2)) # ±1.2 µT

plot.showGrid(x=True, y=True)

plot.setLabel('bottom', xLabel)

plot.setLabel('left', yLabel)

elif 'gyro' in key:

plot.showGrid(x=True, y=True)

plot.setLabel('bottom', xLabel)

plot.setLabel('left', yLabel)

plot.setRange(yRange=(-5, 5)) # ±0.1 °/s for calibrated gyro

curveItems[key] = plot.plot(pen=pg.mkPen('b', width=2))

plotGrid.addWidget(plot, idx // 3, idx % 3)

plots[key] = plot

mainLayout.addLayout(plotGrid)

buttonLayout = QtWidgets.QHBoxLayout()

calibrateGyroButton = QtWidgets.QPushButton("Calibrate Gyro")

calibrateGyroButton.setMinimumSize(200, 50)

calibrateGyroButton.setStyleSheet("background-color: #00FF00; color: black; font-size: 16px;")

calibrateAccButton = QtWidgets.QPushButton("Calibrate Accelerometer")

calibrateAccButton.setMinimumSize(200, 50)

calibrateAccButton.setStyleSheet("background-color: #FFFF00; color: black; font-size: 16px;")

calibrateMagButton = QtWidgets.QPushButton("Calibrate Magnetometer")

calibrateMagButton.setMinimumSize(200, 50)

calibrateMagButton.setStyleSheet("background-color: #FFFF00; color: black; font-size: 16px;")

saveCalButton = QtWidgets.QPushButton("Save Calibration")

saveCalButton.setMinimumSize(200, 50)

saveCalButton.setStyleSheet("background-color: #0000FF; color: white; font-size: 16px;")

generateCodeButton = QtWidgets.QPushButton("Generate Code")

generateCodeButton.setMinimumSize(200, 50)

generateCodeButton.setStyleSheet("background-color: #0000FF; color: white; font-size: 16px;")

stopButton = QtWidgets.QPushButton("Stop")

stopButton.setMinimumSize(200, 50)

stopButton.setStyleSheet("background-color: #FF0000; color: white; font-size: 16px;")

buttonLayout.addWidget(calibrateGyroButton)

buttonLayout.addWidget(calibrateAccButton)

buttonLayout.addWidget(calibrateMagButton)

buttonLayout.addWidget(saveCalButton)

buttonLayout.addWidget(generateCodeButton)

buttonLayout.addWidget(stopButton)

mainLayout.addLayout(buttonLayout)# --- 3D Magnetometer and Attitude Window ---

mag3DWindow = QtWidgets.QWidget()

mag3DWindow.setWindowTitle("3D Magnetic Field Vector and Attitude (µT, °)")

mag3DWindow.setMinimumSize(800, 800)

mag3DLayout = QtWidgets.QGridLayout()

mag3DWindow.setLayout(mag3DLayout)

mag3DView = GLViewWidget()

mag3DView.setCameraPosition(distance=3, elevation=30, azimuth=45)

mag3DLayout.addWidget(mag3DView, 0, 0)

sphereMesh = gl.MeshData.sphere(rows=20, cols=20, radius=1.0)

sphere = gl.GLMeshItem(meshdata=sphereMesh, smooth=True, color=(0.3, 0.3, 0.3, 0.2), shader='shaded', drawFaces=True)

mag3DView.addItem(sphere)

circleMesh = gl.MeshData.cylinder(rows=1, cols=50, radius=[1.0, 1.0], length=0.001)

xyCircle = gl.GLMeshItem(meshdata=circleMesh, smooth=True, color=(1, 0.5, 0, 0.4), shader='shaded', glOptions='additive')

xyCircle.rotate(90, 1, 0, 0)

xyCircle.setDepthValue(-5)

mag3DView.addItem(xyCircle)

for axis, color in zip([(1.2, 0, 0), (0, 1.2, 0), (0, 0, 1.2)], [(1, 0, 0, 1), (0, 1, 0, 1), (0, 0, 1, 1)]):

line = gl.GLLinePlotItem(pos=np.array([[0, 0, 0], axis]), color=color, width=2, antialias=True)

mag3DView.addItem(line)

vectorArrow = gl.GLLinePlotItem(pos=np.array([[0, 0, 0], [0, 0, 0]]), color=(1, 0, 0, 1), width=3, antialias=True)

vectorArrow.setDepthValue(10)

mag3DView.addItem(vectorArrow)

xyProjection = gl.GLLinePlotItem(pos=np.array([[0, 0, 0], [0, 0, 0]]), color=(0, 1, 1, 1), width=2, antialias=True)

xyProjection.setDepthValue(10)

mag3DView.addItem(xyProjection)

verticalComponent = gl.GLLinePlotItem(pos=np.array([[0, 0, 0], [0, 0, 0]]), color=(1, 0, 1, 1), width=2, antialias=True)

verticalComponent.setDepthValue(10)

mag3DView.addItem(verticalComponent)

vectorTrail = gl.GLLinePlotItem(pos=np.array([[0, 0, 0]]), color=(1, 1, 0, 0.6), width=1, antialias=True)

vectorTrail.setDepthValue(10)

mag3DView.addItem(vectorTrail)

attitudePlots = {}

attitudePlotTitles = [

('rollPlot', 'Roll (°)', '', ''),

('pitchPlot', 'Pitch (°)', '', ''),

('yawPlot', 'Yaw (°)', '', '')

]

for idx, (key, title, xLabel, yLabel) in enumerate(attitudePlotTitles):

plot = pg.PlotWidget(title=title)

plot.setMinimumSize(200, 200)

plot.setRange(xRange=(-1.5, 1.5), yRange=(-1.5, 1.5))

plot.setAspectLocked(True)

plot.hideAxis('bottom')

plot.hideAxis('left')

readout = pg.TextItem("0.0°", anchor=(0.5, 0.5), color=(0, 255, 0))

readout.setFont(QtGui.QFont("Courier New", 14, QtGui.QFont.Bold))

if key in ['rollPlot', 'pitchPlot']:

readout.setPos(0, -1.4)

else:

readout.setPos(0, -1.5)

readout.setZValue(15)

plot.addItem(readout)

attitudeItems[f'{key}_readout'] = readout

if key == 'rollPlot':

skyX = np.array([-1.5, 1.5, 1.5, -1.5])

skyY = np.array([0, 0, 1.5, 1.5])

groundX = np.array([-1.5, 1.5, 1.5, -1.5])

groundY = np.array([-1.5, -1.5, 0, 0])

sky = pg.PlotDataItem(x=skyX, y=skyY, pen=None, fillLevel=1.5, brush=pg.mkBrush(0, 191, 255, 255))

ground = pg.PlotDataItem(x=groundX, y=groundY, pen=None, fillLevel=-1.5, brush=pg.mkBrush(139, 69, 19, 255))

plot.addItem(sky)

plot.addItem(ground)

horizon = pg.PlotDataItem(x=[-1, 1], y=[0, 0], pen=pg.mkPen(color=(0, 100, 0), width=3))

plot.addItem(horizon)

attitudeItems['roll_horizon'] = horizon

for xPos, anchor in [(-1.2, (1, 0.5)), (1.2, (0, 0.5))]:

text = pg.TextItem("0°", anchor=anchor, color=(255, 255, 0))

text.setFont(QtGui.QFont("Arial", 12, QtGui.QFont.Bold))

text.setPos(xPos, 0)

text.setZValue(10)

plot.addItem(text)

for angle in [30, 60]:

rad = math.radians(angle)

sinRad = math.sin(rad)

cosRad = math.cos(rad)

text = pg.TextItem(f"{angle}°", anchor=(0, 0.5), color=(255, 255, 0))

text.setFont(QtGui.QFont("Arial", 12, QtGui.QFont.Bold))

text.setPos(1.2 * cosRad, 1.2 * sinRad)

text.setZValue(10)

plot.addItem(text)

text = pg.TextItem(f"{angle}°", anchor=(1, 0.5), color=(255, 255, 0))

text.setFont(QtGui.QFont("Arial", 12, QtGui.QFont.Bold))

text.setPos(-1.2 * cosRad, 1.2 * sinRad)

text.setZValue(10)

plot.addItem(text)

text = pg.TextItem(f"-{angle}°", anchor=(1, 0.5), color=(255, 255, 0))

text.setFont(QtGui.QFont("Arial", 12, QtGui.QFont.Bold))

text.setPos(-1.2 * cosRad, -1.2 * sinRad)

text.setZValue(10)

plot.addItem(text)

text = pg.TextItem(f"-{angle}°", anchor=(0, 0.5), color=(255, 255, 0))

text.setFont(QtGui.QFont("Arial", 12, QtGui.QFont.Bold))

text.setPos(1.2 * cosRad, -1.2 * sinRad)

text.setZValue(10)

plot.addItem(text)

elif key == 'pitchPlot':

skyX = np.array([-1.5, 1.5, 1.5, -1.5])

skyY = np.array([0, 0, 1.5, 1.5])

groundX = np.array([-1.5, 1.5, 1.5, -1.5])

groundY = np.array([-1.5, -1.5, 0, 0])

sky = pg.PlotDataItem(x=skyX, y=skyY, pen=None, fillLevel=1.5, brush=pg.mkBrush(0, 191, 255, 255))

ground = pg.PlotDataItem(x=groundX, y=groundY, pen=None, fillLevel=-1.5, brush=pg.mkBrush(139, 69, 19, 255))

plot.addItem(sky)

plot.addItem(ground)

ladder = []

for angle in [-90, -60, -30, -10, 0, 10, 30, 60, 90]:

y = angle / 90 * 1.2

if angle == 0:

line = pg.PlotDataItem(x=[-1, 1], y=[y, y], pen=pg.mkPen(color=(0, 100, 0), width=3))

else:

line = pg.PlotDataItem(x=[-0.5, -0.2, -0.2, 0.2, 0.2, 0.5], y=[y, y, y+0.05, y+0.05, y, y], pen=pg.mkPen(color=(0, 100, 0), width=2))

textLeft = pg.TextItem(f"{angle}°", anchor=(1, 0.5), color=(255, 255, 0))

textLeft.setFont(QtGui.QFont("Arial", 12, QtGui.QFont.Bold))

textLeft.setPos(-0.6, y)

textRight = pg.TextItem(f"{angle}°", anchor=(0, 0.5), color=(255, 255, 0))

textRight.setFont(QtGui.QFont("Arial", 12, QtGui.QFont.Bold))

textRight.setPos(0.6, y)

plot.addItem(textLeft)

plot.addItem(textRight)

plot.addItem(line)

ladder.append(line)

attitudeItems['pitch_ladder'] = ladder

elif key == 'yawPlot':

theta = np.linspace(0, 2 * np.pi, 100)

xCircle = 1.2 * np.sin(theta)

yCircle = 1.2 * np.cos(theta)

circle = pg.PlotDataItem(x=xCircle, y=yCircle, pen=pg.mkPen('w', width=2), fillLevel=0, brush=pg.mkBrush(0, 0, 0, 255))

plot.addItem(circle)

for angle, label in [(0, 'N'), (90, 'E'), (180, 'S'), (270, 'W')]:

rad = math.radians(angle)

x = 1.3 * math.sin(rad)

y = 1.3 * math.cos(rad)

text = pg.TextItem(label, anchor=(0.5, 0.5), color=(255, 255, 0))

text.setFont(QtGui.QFont("Arial", 12))

text.setPos(x, y)

plot.addItem(text)

needle = pg.PlotDataItem(x=[0, 0], y=[0, 1], pen=pg.mkPen('r', width=3))

plot.addItem(needle)

attitudeItems['yaw_needle'] = needle

if key == 'rollPlot':

mag3DLayout.addWidget(plot, 0, 1)

elif key == 'pitchPlot':

mag3DLayout.addWidget(plot, 1, 0)

elif key == 'yawPlot':

mag3DLayout.addWidget(plot, 1, 1)

attitudePlots[key] = plot# --- Calibrate Gyroscope ---

def calibrateGyro():

global gxOffset, gyOffset, gzOffset

msg = QtWidgets.QMessageBox()

msg.setWindowTitle("Calibrate Gyro")

msg.setText("Keep the device still for calibration. Press OK to start.")

msg.exec_()

gxSamples = []

gySamples = []

gzSamples = []

sampleCount = 0

ser.reset_input_buffer()

while sampleCount < 200:

if ser.in_waiting <= 0: continue

try:

line = ser.readline().decode('utf-8').strip()

values = line.split(',')

if len(values) != 9: continue

ax, ay, az, gx, gy, gz, mx, my, mz = map(float, values)

# Convert gyro data from rad/s to °/s

gx = gx * 180.0 / math.pi

gy = gy * 180.0 / math.pi

gz = gz * 180.0 / math.pi

gxSamples.append(gx)

gySamples.append(gy)

gzSamples.append(gz)

sampleCount += 1

except Exception:

pass

time.sleep(0.01)

if not gxSamples: return

gxOffset = np.mean(gxSamples) # Offset in °/s

gyOffset = np.mean(gySamples) # Offset in °/s

gzOffset = np.mean(gzSamples) # Offset in °/s

try:

with open('gCal.txt', 'w') as f:

f.write(f"{gxOffset},{gyOffset},{gzOffset}\n")

msg = QtWidgets.QMessageBox()

msg.setWindowTitle("Gyro Calibration Complete")

msg.setText(f"Offsets (°/s): Gx={gxOffset:.6f}, Gy={gyOffset:.6f}, Gz={gzOffset:.6f}\nSaved to gCal.txt")

msg.exec_()

generateArduinoCode()

except Exception as e:

msg = QtWidgets.QMessageBox()

msg.setWindowTitle("Gyro Calibration Error")

msg.setText(f"Error saving gyro offsets: {str(e)}")

msg.exec_()# --- Calibrate Accelerometer ---

def calibrateAcc():

global accCalibrating, accMin, accMax, accOffset, accScale, accRaw, axSamples, aySamples, azSamples, plots

if accCalibrating:

calibrateAccButton.setText("Calibrate Accelerometer")

accCalibrating = False

if axSamples:

accMin['x'] = min(axSamples)

accMin['y'] = min(aySamples)

accMin['z'] = min(azSamples)

accMax['x'] = max(axSamples)

accMax['y'] = max(aySamples)

accMax['z'] = max(azSamples)

accOffset['x'] = (accMin['x'] + accMax['x']) / 2.0

accOffset['y'] = (accMin['y'] + accMax['y']) / 2.0

accOffset['z'] = (accMin['z'] + accMax['z']) / 2.0

rangeX = accMax['x'] - accMin['x']

rangeY = accMax['y'] - accMin['y']

rangeZ = accMax['z'] - accMin['z']

avgRange = (rangeX + rangeY + rangeZ) / 3.0

accScale['x'] = 2.0 / avgRange if avgRange != 0 else 1.0

accScale['y'] = 2.0 / avgRange if avgRange != 0 else 1.0

accScale['z'] = 2.0 / avgRange if avgRange != 0 else 1.0

if avgRange < 0.5 or avgRange > 20.0:

msg = QtWidgets.QMessageBox()

msg.setWindowTitle("Calibration Warning")

msg.setText(f"Average range {avgRange:.6f} is unusual.\nEnsure full 3D rotation during calibration.")

msg.exec_()

accRaw['x'] = np.empty(0)

accRaw['y'] = np.empty(0)

accRaw['z'] = np.empty(0)

try:

with open('accCal.txt', 'w') as f:

f.write(f"{accOffset['x']},{accScale['x']},{accOffset['y']},{accScale['y']},{accOffset['z']},{accScale['z']}\n")

msg = QtWidgets.QMessageBox()

msg.setWindowTitle("Acc Calibration Complete")

msg.setText(f"Offsets (m/s²): Ax={accOffset['x']:.6f}, Ay={accOffset['y']:.6f}, Az={accOffset['z']:.6f}\n" +

f"Scales: Ax={accScale['x']:.6f}, Ay={accScale['y']:.6f}, Az={accScale['z']:.6f}\nSaved to accCal.txt")

msg.exec_()

generateArduinoCode()

except Exception as e:

msg = QtWidgets.QMessageBox()

msg.setWindowTitle("Acc Calibration Error")

msg.setText(f"Error saving acc offsets: {str(e)}")

msg.exec_()

for key in ['accXY', 'accYZ', 'accXZ']:

plots[key].setRange(xRange=(-1.2, 1.2), yRange=(-1.2, 1.2))

return

accCalibrating = True

accMin = {'x': float('inf'), 'y': float('inf'), 'z': float('inf')}

accMax = {'x': float('-inf'), 'y': float('-inf'), 'z': float('-inf')}

axSamples = []

aySamples = []

azSamples = []

accRaw['x'] = np.empty(0)

accRaw['y'] = np.empty(0)

accRaw['z'] = np.empty(0)

calibrateAccButton.setText("Stop Acc Calibration")

msg = QtWidgets.QMessageBox()

msg.setWindowTitle("Accelerometer Calibration")

msg.setText("Rotate device in all directions (full 3D rotation) to capture min/max values for all axes.")

msg.exec_()# --- Calibrate Magnetometer ---

def calibrateMag():

global magCalibrating, magMin, magMax, magOffset, magScale, magRaw, mxSamples, mySamples, mzSamples, magRawMin, magRawMax, plots, mag3DView, vectorArrow, vectorTrail, xyProjection, verticalComponent, trailBuffer

if magCalibrating:

calibrateMagButton.setText("Calibrate Magnetometer")

magCalibrating = False

if mxSamples:

magMin['x'] = min(mxSamples)

magMin['y'] = min(mySamples)

magMin['z'] = min(mzSamples)

magMax['x'] = max(mxSamples)

magMax['y'] = max(mySamples)

magMax['z'] = max(mzSamples)

# --- CENTER OFFSET (unchanged) ---

magOffset['x'] = (magMin['x'] + magMax['x']) / 2.0

magOffset['y'] = (magMin['y'] + magMax['y']) / 2.0

magOffset['z'] = (magMin['z'] + magMax['z']) / 2.0

# --- PER-AXIS SCALING TO ±1.0 (NEW) ---

rangeX = magMax['x'] - magMin['x']

rangeY = magMax['y'] - magMin['y']

rangeZ = magMax['z'] - magMin['z']

magScale['x'] = 2.0 / rangeX if rangeX > 1e-6 else 1.0

magScale['y'] = 2.0 / rangeY if rangeY > 1e-6 else 1.0

magScale['z'] = 2.0 / rangeZ if rangeZ > 1e-6 else 1.0

# Clear buffers

magRaw['x'] = np.empty(0)

magRaw['y'] = np.empty(0)

magRaw['z'] = np.empty(0)

magRawMin = {'x': float('inf'), 'y': float('inf'), 'z': float('inf')}

magRawMax = {'x': float('-inf'), 'y': float('-inf'), 'z': float('-inf')}

trailBuffer = []

vectorArrow.setData(pos=np.array([[0, 0, 0], [0, 0, 0]]))

vectorTrail.setData(pos=np.array([[0, 0, 0]]))

xyProjection.setData(pos=np.array([[0, 0, 0], [0, 0, 0]]))

verticalComponent.setData(pos=np.array([[0, 0, 0], [0, 0, 0]]))

try:

with open('magCal.txt', 'w') as f:

f.write(f"{magOffset['x']},{magScale['x']},{magOffset['y']},{magScale['y']},{magOffset['z']},{magScale['z']}\n")

msg = QtWidgets.QMessageBox()

msg.setWindowTitle("Mag Calibration Complete")

msg.setText(

f"Offsets (arb. units): Mx={magOffset['x']:.6f}, My={magOffset['y']:.6f}, Mz={magOffset['z']:.6f}\n"

f"Scales (per-axis to ±1): X={magScale['x']:.6f}, Y={magScale['y']:.6f}, Z={magScale['z']:.6f}\n"

f"Saved to magCal.txt\n"

f"Your XZ circle will now be perfectly round from -1 to +1"

)

msg.exec_()

generateArduinoCode()

except Exception as e:

msg = QtWidgets.QMessageBox()

msg.setWindowTitle("Mag Calibration Error")

msg.setText(f"Error saving mag offsets: {str(e)}")

msg.exec_()

for key in ['magXY', 'magYZ', 'magXZ']:

plots[key].setRange(xRange=(-1.2, 1.2), yRange=(-1.2, 1.2))

mag3DView.opts['distance'] = 3

mag3DView.setCameraPosition(distance=3, elevation=30, azimuth=45)

return

# --- Start Calibration ---

magCalibrating = True

magMin = {'x': float('inf'), 'y': float('inf'), 'z': float('inf')}

magMax = {'x': float('-inf'), 'y': float('-inf'), 'z': float('-inf')}

mxSamples = []

mySamples = []

mzSamples = []

magRaw['x'] = np.empty(0)

magRaw['y'] = np.empty(0)

magRaw['z'] = np.empty(0)

magRawMin = {'x': float('inf'), 'y': float('inf'), 'z': float('inf')}

magRawMax = {'x': float('-inf'), 'y': float('-inf'), 'z': float('-inf')}

trailBuffer = []

vectorArrow.setData(pos=np.array([[0, 0, 0], [0, 0, 0]]))

vectorTrail.setData(pos=np.array([[0, 0, 0]]))

xyProjection.setData(pos=np.array([[0, 0, 0], [0, 0, 0]]))

verticalComponent.setData(pos=np.array([[0, 0, 0], [0, 0, 0]]))

calibrateMagButton.setText("Stop Mag Calibration")

msg = QtWidgets.QMessageBox()

msg.setWindowTitle("Magnetometer Calibration")

msg.setText("Rotate device in figure-8 pattern to capture min/max values for all axes.\n"

"After calibration, XZ circle will be forced to ±1.0")

msg.exec_()

def generateCode():

success = generateArduinoCode(to_file=True)

msg = QtWidgets.QMessageBox()

msg.setWindowTitle("Generate Code")

if success:

msg.setText("Arduino calibration function saved to calData.txt")

else:

msg.setText("Error saving calData.txt.")

msg.exec_()# --- Stop Program ---

def stopProgram():

try:

plotTimer.stop()

if ser.is_open:

ser.close()

mainWindow.close()

mag3DWindow.close()

app.exit(0)

except Exception as e:

msg = QtWidgets.QMessageBox()

msg.setWindowTitle("Stop Error")

msg.setText(f"Error stopping program: {str(e)}")

msg.exec_()# --- Update Plots ---

def updatePlots():

global accRaw, gyroRaw, magRaw, timePoints, gxOffset, gyOffset, gzOffset

global accCalibrating, magCalibrating, accMin, accMax, magMin, magMax

global accOffset, accScale, magOffset, magScale, accFiltered, magFiltered

global axSamples, aySamples, azSamples, mxSamples, mySamples, mzSamples

global magRawMin, magRawMax, vectorArrow, vectorTrail, xyProjection, verticalComponent, trailBuffer

global attitudeItems, attitudePlots

if ser.in_waiting <= 0: return

try:

line = ser.readline().decode('utf-8').strip()

values = line.split(',')

if len(values) != 9: return

ax, ay, az, gx, gy, gz, mx, my, mz = map(float, values)

# Convert gyro data from rad/s to °/s

gx = gx * 180.0 / math.pi

gy = gy * 180.0 / math.pi

gz = gz * 180.0 / math.pi

# Apply low-pass filter to accelerometer data

accFiltered['x'] = alpha * ax + (1 - alpha) * accFiltered['x'] if accFiltered['x'] is not None else ax

accFiltered['y'] = alpha * ay + (1 - alpha) * accFiltered['y'] if accFiltered['y'] is not None else ay

accFiltered['z'] = alpha * az + (1 - alpha) * accFiltered['z'] if accFiltered['z'] is not None else az

ax = accFiltered['x'] # m/s²

ay = accFiltered['y']

az = accFiltered['z']

# Apply low-pass filter to magnetometer data

magFiltered['x'] = alpha * mx + (1 - alpha) * magFiltered['x'] if magFiltered['x'] is not None else mx

magFiltered['y'] = alpha * my + (1 - alpha) * magFiltered['y'] if magFiltered['y'] is not None else my

magFiltered['z'] = alpha * mz + (1 - alpha) * magFiltered['z'] if magFiltered['z'] is not None else mz

mx = magFiltered['x'] # QMC5883L arbitrary units

my = magFiltered['y']

mz = magFiltered['z']

# Collect samples during calibration

if accCalibrating:

axSamples.append(ax)

aySamples.append(ay)

azSamples.append(az)

accMin['x'] = min(accMin['x'], ax)

accMin['y'] = min(accMin['y'], ay)

accMin['z'] = min(accMin['z'], az)

accMax['x'] = max(accMax['x'], ax)

accMax['y'] = max(accMax['y'], ay)

accMax['z'] = max(accMax['z'], az)

if magCalibrating:

mxSamples.append(mx)

mySamples.append(my)

mzSamples.append(mz)

magMin['x'] = min(magMin['x'], mx)

magMin['y'] = min(magMin['y'], my)

magMin['z'] = min(magMin['z'], mz)

magMax['x'] = max(magMax['x'], mx)

magMax['y'] = max(magMax['y'], my)

magMax['z'] = max(magMax['z'], mz)

# Apply calibration

axCal = (ax - accOffset['x']) * accScale['x'] # m/s²

ayCal = (ay - accOffset['y']) * accScale['y']

azCal = (az - accOffset['z']) * accScale['z']

gxCal = gx - gxOffset # °/s

gyCal = gy - gyOffset

gzCal = gz - gzOffset

mxCal = (mx - magOffset['x']) * magScale['x'] # µT

myCal = (my - magOffset['y']) * magScale['y']

mzCal = (mz - magOffset['z']) * magScale['z']

# Determine accelerometer data to plot

if accCalibrating:

ax_plot = ax

ay_plot = ay

az_plot = az

else:

ax_plot = axCal

ay_plot = ayCal

az_plot = azCal

# Determine magnetometer data to plot

if magCalibrating:

mx_plot = mx

my_plot = my

mz_plot = mz

else:

mx_plot = mxCal

my_plot = myCal

mz_plot = mzCal

# Calculate roll and pitch from accelerometer (NED: x north, y east, z down)

roll = math.atan2(ayCal, azCal + epsilon) * 180 / math.pi # °

pitch = math.atan2(-axCal, math.sqrt(ayCal**2 + azCal**2 + epsilon)) * 180 / math.pi # °

phi = math.radians(roll)

theta = math.radians(pitch)

# Compute tilt-compensated yaw

mxH = mxCal * math.cos(theta) + myCal * math.sin(phi) * math.sin(theta) + mzCal * math.cos(phi) * math.sin(theta)

myH = myCal * math.cos(phi) - mzCal * math.sin(phi)

yaw = math.atan2(myH, mxH + epsilon) * 180 / math.pi

if yaw < 0:

yaw += 360 # Normalize to 0-360°

# Update attitude readouts

attitudeItems['rollPlot_readout'].setText(f"Roll: {-roll:+.1f}°")

attitudeItems['pitchPlot_readout'].setText(f"Pitch: {-pitch:+.1f}°")

attitudeItems['yawPlot_readout'].setText(f"Yaw: {yaw:.1f}°") # Update 3D magnetic vector visualization

vec = np.array([mx_plot, my_plot, mz_plot])

norm = np.linalg.norm(vec)

if norm > epsilon:

unitVec = vec / norm

vectorArrow.setData(pos=np.array([[0, 0, 0], unitVec]), color=(1, 0, 0, 1), width=3)

xyProj = np.array([unitVec[0], unitVec[1], 0])

xyProjection.setData(pos=np.array([[0, 0, 0], xyProj]), color=(0, 1, 1, 1), width=2)

verticalComponent.setData(pos=np.array([xyProj, unitVec]), color=(1, 0, 1, 1), width=2)

trailBuffer.append(unitVec)

trailBuffer = trailBuffer[-trailMaxPoints:]

vectorTrail.setData(pos=np.array(trailBuffer), color=(1, 1, 0, 0.6), width=1)

# Update plot ranges for accelerometer if in raw mode

if accCalibrating or (accScale['x'] == 1.0 and accOffset['x'] == 0.0):

accRawMin = {'x': min(accRaw['x'], default=ax_plot) if len(accRaw['x']) > 0 else ax_plot,

'y': min(accRaw['y'], default=ay_plot) if len(accRaw['y']) > 0 else ay_plot,

'z': min(accRaw['z'], default=az_plot) if len(accRaw['z']) > 0 else az_plot}

accRawMax = {'x': max(accRaw['x'], default=ax_plot) if len(accRaw['x']) > 0 else ax_plot,

'y': max(accRaw['y'], default=ay_plot) if len(accRaw['y']) > 0 else ay_plot,

'z': max(accRaw['z'], default=az_plot) if len(accRaw['z']) > 0 else az_plot}

xMin = accRawMin['x'] * 1.1

xMax = accRawMax['x'] * 1.1

yMin = accRawMin['y'] * 1.1

yMax = accRawMax['y'] * 1.1

zMin = accRawMin['z'] * 1.1

zMax = accRawMax['z'] * 1.1

plots['accXY'].setRange(xRange=(xMin, xMax), yRange=(yMin, yMax))

plots['accYZ'].setRange(xRange=(yMin, yMax), yRange=(zMin, zMax))

plots['accXZ'].setRange(xRange=(xMin, xMax), yRange=(zMin, zMax))

# Update plot ranges for magnetometer if in raw mode

use_raw_mag_range = magCalibrating or (magScale['x'] == 1.0 and magOffset['x'] == 0.0)

if use_raw_mag_range:

magRawMin['x'] = min(magRawMin['x'], mx)

magRawMax['x'] = max(magRawMax['x'], mx)

magRawMin['y'] = min(magRawMin['y'], my)

magRawMax['y'] = max(magRawMax['y'], my)

magRawMin['z'] = min(magRawMin['z'], mz)

magRawMax['z'] = max(magRawMax['z'], mz)

xMin = magRawMin['x'] * 1.1

xMax = magRawMax['x'] * 1.1

yMin = magRawMin['y'] * 1.1

yMax = magRawMax['y'] * 1.1

zMin = magRawMin['z'] * 1.1

zMax = magRawMax['z'] * 1.1

mag3DView.opts['distance'] = max(xMax - xMin, yMax - yMin, zMax - zMin) * 1.5

mag3DView.setCameraPosition(distance=mag3DView.opts['distance'])

plots['magXY'].setRange(xRange=(xMin, xMax), yRange=(yMin, yMax))

plots['magYZ'].setRange(xRange=(yMin, yMax), yRange=(zMin, zMax))

plots['magXZ'].setRange(xRange=(xMin, xMax), yRange=(zMin, zMax))

# Store data

accRaw['x'] = np.append(accRaw['x'], ax_plot)[-accMagMaxPoints:]

accRaw['y'] = np.append(accRaw['y'], ay_plot)[-accMagMaxPoints:]

accRaw['z'] = np.append(accRaw['z'], az_plot)[-accMagMaxPoints:]

gyroRaw['x'] = np.append(gyroRaw['x'], gxCal)[-gyroMaxPoints:]

gyroRaw['y'] = np.append(gyroRaw['y'], gyCal)[-gyroMaxPoints:]

gyroRaw['z'] = np.append(gyroRaw['z'], gzCal)[-gyroMaxPoints:]

magRaw['x'] = np.append(magRaw['x'], mx_plot)[-accMagMaxPoints:]

magRaw['y'] = np.append(magRaw['y'], my_plot)[-accMagMaxPoints:]

magRaw['z'] = np.append(magRaw['z'], mz_plot)[-accMagMaxPoints:]

elapsed = startTime.msecsTo(QtCore.QTime.currentTime()) / 1000.0

timePoints = np.append(timePoints, elapsed)[-gyroMaxPoints:]

# Update 2D scatter plots

scatterItems['accXY'].setData(x=accRaw['x'], y=accRaw['y'])

scatterItems['accYZ'].setData(x=accRaw['y'], y=accRaw['z'])

scatterItems['accXZ'].setData(x=accRaw['x'], y=accRaw['z'])

scatterItems['magXY'].setData(x=magRaw['x'], y=magRaw['y'])

scatterItems['magYZ'].setData(x=magRaw['y'], y=magRaw['z'])

scatterItems['magXZ'].setData(x=magRaw['x'], y=magRaw['z'])

if len(timePoints) <= 0: return

xMin = max(0, timePoints[-1] - gyroTimeWindow)

xMax = timePoints[-1]

for key in ['gyroX', 'gyroY', 'gyroZ']:

plots[key].setRange(xRange=(xMin, xMax))

curveItems[key].setData(x=timePoints, y=gyroRaw[key[-1].lower()])

# Update roll horizon

rollRad = math.radians(roll)

x1 = -1 * math.cos(rollRad)

y1 = 1 * math.sin(rollRad)

x2 = 1 * math.cos(rollRad)

y2 = -1 * math.sin(rollRad)

attitudeItems['roll_horizon'].setData(x=[x1, x2], y=[y1, y2])

# Update pitch ladder

pitchOffset = -pitch / 90 * 1.2

for idx, angle in enumerate([-90, -60, -30, -10, 0, 10, 30, 60, 90]):

yBase = angle / 90 * 1.2

yShifted = yBase + pitchOffset

if angle == 0:

attitudeItems['pitch_ladder'][idx].setData(x=[-1, 1], y=[yShifted, yShifted])

else:

attitudeItems['pitch_ladder'][idx].setData(x=[-0.5, -0.2, -0.2, 0.2, 0.2, 0.5], y=[yShifted, yShifted, yShifted+0.05, yShifted+0.05, yShifted, yShifted])

# Update yaw needle

yawRad = math.radians(yaw)

needleX = 1 * math.sin(yawRad)

needleY = 1 * math.cos(yawRad)

attitudeItems['yaw_needle'].setData(x=[0, needleX], y=[0, needleY])

except Exception:

pass# --- Connect Buttons and Start Application ---

calibrateGyroButton.clicked.connect(calibrateGyro)

calibrateAccButton.clicked.connect(calibrateAcc)

calibrateMagButton.clicked.connect(calibrateMag)

saveCalButton.clicked.connect(saveCalibration)

generateCodeButton.clicked.connect(generateCode)

stopButton.clicked.connect(stopProgram)

ser.reset_input_buffer()

loadCalibration()

plotTimer = QtCore.QTimer()

plotTimer.timeout.connect(updatePlots)

plotTimer.start(50)

mainWindow.show()

mag3DWindow.show()

try:

app.exec_()

except Exception as e:

msg = QtWidgets.QMessageBox()

msg.setWindowTitle("Application Error")

msg.setText(f"Application error: {str(e)}")

msg.exec_()

finally:

if ser.is_open:

ser.close()

Then finally we take the calibration parameters from the python program, and incorporate them on the Arduino side to allow reading the data from the sensors, and reporting calibrated numbers. Remember, in the program below, you should use your calibration parameters instead of mine. That is, edit the program below for your specific calibration numbers.

#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>
#include <Wire.h>
#include <QMC5883LCompass.h>
float AxRaw,AyRaw,AzRaw,GxRaw,GyRaw,GzRaw,MxRaw,MyRaw,MzRaw;
float AxCal,AyCal,AzCal,GxCal,GyCal,GzCal,MxCal,MyCal,MzCal;
Adafruit_MPU6050 mpu;
QMC5883LCompass compass;

void setup() {
  // put your setup code here, to run once:
Serial.begin(115200);
mpu.begin();
mpu.setI2CBypass(true);
compass.init();
mpu.setGyroRange(MPU6050_RANGE_1000_DEG);
delay(100);
}

void calibrateSensors() {
  const float axOffset = 0.45407887789180545;
  const float ayOffset = 0.09432915233553185;
  const float azOffset = -0.4614157209191969;
  const float axScale = 0.10141341897341144;
  const float ayScale = 0.10141341897341144;
  const float azScale = 0.10141341897341144;
  const float gxOffset = -2.277507235645022;
  const float gyOffset = 0.8794902155258137;
  const float gzOffset = -0.5729577951308232;
  const float mxOffset = -125.54461152573242;
  const float myOffset = 124.52589039569995;
  const float mzOffset = 965.8106108557855;
  const float mxScale = 0.0010185143396312232;
  const float myScale = 0.0010185143396312232;
  const float mzScale = 0.0010185143396312232;
    AxCal = (AxRaw - axOffset) * axScale;
    AyCal = (AyRaw - ayOffset) * ayScale;
    AzCal = (AzRaw - azOffset) * azScale;
    GxCal = GxRaw*180/PI - gxOffset;
    GyCal = GyRaw*180/PI - gyOffset;
    GzCal = GzRaw*180/PI - gzOffset;
    MxCal = (MxRaw - mxOffset) * mxScale;
    MyCal = (MyRaw - myOffset) * myScale;
    MzCal = (MzRaw - mzOffset) * mzScale;
}


void loop() {
  // put your main code here, to run repeatedly:
compass.read();
sensors_event_t a, g, temp;
mpu.getEvent(&a, &g, &temp);

AxRaw = a.acceleration.x;
AyRaw = a.acceleration.y;
AzRaw = a.acceleration.z;

GxRaw = g.gyro.x;
GyRaw = g.gyro.y;
GzRaw = g.gyro.z;

MxRaw= compass.getX();
MyRaw= compass.getY();
MzRaw= compass.getZ();

calibrateSensors();

Serial.print(AxCal);
Serial.print(',');
Serial.print(AyCal);
Serial.print(',');
Serial.print(AzCal);
Serial.print(',');
Serial.print(GxCal);
Serial.print(',');
Serial.print(GyCal);
Serial.print(',');
Serial.print(GzCal);
Serial.print(',');
Serial.print(MxCal);
Serial.print(',');
Serial.print(MyCal);
Serial.print(',');
Serial.println(MzCal);
delay(100);
}

#include <Adafruit_MPU6050.h>

#include <Adafruit_Sensor.h>

#include <Wire.h>

#include <QMC5883LCompass.h>

float AxRaw,AyRaw,AzRaw,GxRaw,GyRaw,GzRaw,MxRaw,MyRaw,MzRaw;

float AxCal,AyCal,AzCal,GxCal,GyCal,GzCal,MxCal,MyCal,MzCal;

Adafruit_MPU6050 mpu;

QMC5883LCompass compass;

void setup() {

// put your setup code here, to run once:

Serial.begin(115200);

mpu.begin();

mpu.setI2CBypass(true);

compass.init();

mpu.setGyroRange(MPU6050_RANGE_1000_DEG);

delay(100);

}

void calibrateSensors() {

const float axOffset = 0.45407887789180545;

const float ayOffset = 0.09432915233553185;

const float azOffset = -0.4614157209191969;

const float axScale = 0.10141341897341144;

const float ayScale = 0.10141341897341144;

const float azScale = 0.10141341897341144;

const float gxOffset = -2.277507235645022;

const float gyOffset = 0.8794902155258137;

const float gzOffset = -0.5729577951308232;

const float mxOffset = -125.54461152573242;

const float myOffset = 124.52589039569995;

const float mzOffset = 965.8106108557855;

const float mxScale = 0.0010185143396312232;

const float myScale = 0.0010185143396312232;

const float mzScale = 0.0010185143396312232;

AxCal = (AxRaw - axOffset) * axScale;

AyCal = (AyRaw - ayOffset) * ayScale;

AzCal = (AzRaw - azOffset) * azScale;

GxCal = GxRaw*180/PI - gxOffset;

GyCal = GyRaw*180/PI - gyOffset;

GzCal = GzRaw*180/PI - gzOffset;

MxCal = (MxRaw - mxOffset) * mxScale;

MyCal = (MyRaw - myOffset) * myScale;

MzCal = (MzRaw - mzOffset) * mzScale;

}

void loop() {

// put your main code here, to run repeatedly:

compass.read();

sensors_event_t a, g, temp;

mpu.getEvent(&a, &g, &temp);

AxRaw = a.acceleration.x;

AyRaw = a.acceleration.y;

AzRaw = a.acceleration.z;

GxRaw = g.gyro.x;

GyRaw = g.gyro.y;

GzRaw = g.gyro.z;

MxRaw= compass.getX();

MyRaw= compass.getY();

MzRaw= compass.getZ();

calibrateSensors();

Serial.print(AxCal);

Serial.print(',');

Serial.print(AyCal);

Serial.print(',');

Serial.print(AzCal);

Serial.print(',');

Serial.print(GxCal);

Serial.print(',');

Serial.print(GyCal);

Serial.print(',');

Serial.print(GzCal);

Serial.print(',');

Serial.print(MxCal);

Serial.print(',');

Serial.print(MyCal);

Serial.print(',');

Serial.println(MzCal);

delay(100);

}

Arduino, Python

Improving Digital Compass Accuracy With a Low Pass Filter

October 22, 2025 admin

In this video lesson we add a low pass filter to our calibration and digital compass program. This allows more precise calibration, and removes the jitter from the digital compass display. We continue to use the QMC5883L 3-Axis Magnetometer, which is on our GY-87 IMU module. We are using the following schematic for our project:

We collect the data using the GY-87 connected to an Arduino. Below is the simple program which takes the magnetometer data and sends it to the serial port.

#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>
#include <Wire.h>
#include <QMC5883LCompass.h>
int x,y,z;
Adafruit_MPU6050 mpu;
QMC5883LCompass compass;
void setup() {
Serial.begin(115200);
mpu.begin();
mpu.setI2CBypass(true);
compass.init();
}
void loop() {
 compass.read();
 x = compass.getX();
 y = compass.getY();
 z = compass.getZ();
Serial.print(x);
Serial.print(',');
Serial.print(y);
Serial.print(',');
Serial.println(z);
 delay(100);
}

#include <Adafruit_MPU6050.h>

#include <Adafruit_Sensor.h>

#include <Wire.h>

#include <QMC5883LCompass.h>

int x,y,z;

Adafruit_MPU6050 mpu;

QMC5883LCompass compass;

void setup() {

Serial.begin(115200);

mpu.begin();

mpu.setI2CBypass(true);

compass.init();

}

void loop() {

compass.read();

x = compass.getX();

y = compass.getY();

z = compass.getZ();

Serial.print(x);

Serial.print(',');

Serial.print(y);

Serial.print(',');

Serial.println(z);

delay(100);

}

The code for the Python side to do the calibration and display a Digital Compass is:

import serial
import numpy as np
from PyQt5 import QtWidgets, QtCore, QtGui
import pyqtgraph as pg
import math
serialPort = 'COM8'
baudRate =115200
to =.1
ser =serial.Serial(serialPort, baudRate, timeout=to)
maxPoints = 2000
xRaw = np.empty(0)
yRaw = np.empty(0)
zRaw = np.empty(0)

xCal = np.empty(0)
yCal = np.empty(0)
zCal = np.empty(0)
x=0
y=0
z=0


calibrated = False
offsets = np.zeros(3)
scales = np.ones(3)

app = QtWidgets.QApplication([])
mainWindow = QtWidgets.QWidget()
mainWindow.setWindowTitle("Magnetometer Calibratioin")
mainLayout =QtWidgets.QVBoxLayout()
mainWindow.setLayout(mainLayout)

statusLabel = QtWidgets.QLabel("Program Running: Not Calibrated")
statusLabel.setAlignment(QtCore.Qt.AlignCenter)
statusLabel.setStyleSheet("color: green; font-weight: bold; font-size: 20px;")
mainLayout.addWidget(statusLabel)

minMaxLabel=QtWidgets.QLabel("Min/Max: N/A")
minMaxLabel.setAlignment(QtCore.Qt.AlignCenter)
minMaxLabel.setStyleSheet("color: green; font-weight: bold; font-size: 16px;")
mainLayout.addWidget(minMaxLabel)

calibrateButton = QtWidgets.QPushButton("Start Calibration")
calibrateButton.setCheckable(True)
mainLayout.addWidget(calibrateButton)


plotLayout =QtWidgets.QGridLayout()
mainLayout.addLayout(plotLayout)
xyPlot = pg.PlotWidget(title="XY Plane")
yzPlot = pg.PlotWidget(title="YZ Plane")
xzPlot = pg.PlotWidget(title="XZ Plane")
for plot in [xyPlot, yzPlot, xzPlot]:
    plot.setAspectLocked(True)
    plot.showGrid(x=True, y=True)
    plot.setMinimumSize(300,300)
plotLayout.addWidget(xyPlot, 0,0)
plotLayout.addWidget(yzPlot, 0,1)
plotLayout.addWidget(xzPlot, 1,0)

xyScatter = pg.ScatterPlotItem(size=5)
yzScatter = pg.ScatterPlotItem(size=5)
xzScatter = pg.ScatterPlotItem(size=5)

xyPlot.addItem(xyScatter)
yzPlot.addItem(yzScatter)
xzPlot.addItem(xzScatter)

headingPlot = pg.PlotWidget(title="Compass Heading")
headingPlot.setAspectLocked(True)
headingPlot.showGrid(x=True, y=True)
headingPlot.setMinimumSize(300,300)
headingPlot.hideAxis('left')
headingPlot.hideAxis('bottom')
plotLayout.addWidget(headingPlot,1,1)

compassCircle=pg.EllipseROI([-1.5,-1.5],[3.,3.],pen=pg.mkPen('b',width=4),movable=False, resizable=False)
headingPlot.addItem(compassCircle)
compassCircle.removeHandle(0)
compassCircle.removeHandle(0)
compassCircle.setZValue(0)

arrowShaft=pg.PlotCurveItem( x=[0,0],y=[0,1.5],pen=pg.mkPen('r',width=4))
headingPlot.addItem(arrowShaft)
dot=pg.ScatterPlotItem(pos=[(0,1.5)],width=4,size=10,pen=pg.mkPen('y'),brush=pg.mkBrush('y'))
dot.setZValue(1)
headingPlot.addItem(dot)

for angle, label in zip([0,90,180,270],['E','N','W','S']):
    rad = angle/360*2*math.pi
    xPos = np.cos(rad)*1.8
    yPos = np.sin(rad)*1.8
    text=pg.TextItem(label, anchor = (.5,.5), color='g')
    font=QtGui.QFont()
    font.setBold(True)
    font.setPointSize(12)
    text.setFont(font)
    text.setPos(xPos,yPos)
    headingPlot.addItem(text)
    
liveHeading = pg.TextItem("Heading: 0.0\u00B0",anchor= (.5,.5),color='w')
liveHeading.setFont(font)
liveHeading.setPos(0,-2.2)
liveHeading.setZValue(1)
headingPlot.addItem(liveHeading)


def toggleCalibration():
    global calibrated, xRaw, yRaw, zRaw, xCal, yCal, zCal, offsets, scales
    
    if calibrateButton.isChecked():
        calibrateButton.setText("Stop Calibration")
        statusLabel.setText("Mode: Calibration")
        statusLabel.setStyleSheet("color: red; font-weight: bold; font-size: 20px;")
        minMaxLabel.setText("Min/Max: collecting . . .")
        minMaxLabel.setStyleSheet("color: red; font-weight: bold; font-size: 16px;")
        calibrated = False
        xRaw = np.empty(0)
        yRaw = np.empty(0)
        zRaw = np.empty(0)
    if not calibrateButton.isChecked():
        calibrateButton.setText("Start Calibration")
        statusLabel.setText("Mode: Calibrated")
        statusLabel.setStyleSheet("color: green; font-weight: bold; font-size: 20px;")
        
        rawData = np.column_stack((xRaw,yRaw,zRaw))
        minVals = np.min(rawData, axis=0)
        maxVals = np.max(rawData, axis=0)
        offsets = (maxVals + minVals)/2
        scales = 2.0/(maxVals-minVals)
        minMaxLabel.setStyleSheet("color: green; font-weight: bold; font-size: 16px;")
        minMaxLabel.setText("Min(x,y,z: "+str(minVals.round(2))+" Max(x,y,z): "
                            +str(maxVals.round(2))+" Offsets(x,y,z): "+str(offsets.round(2))
                            +"Scales(x,y,z): "+str(scales.round(5)))
        print("Calibration Completed.")
        print("Offsets: ", offsets)
        print("Scales: ", scales)
        
        xCal = np.empty(0)
        yCal = np.empty(0)
        zCal = np.empty(0)
        calibrated = True

calibrateButton.clicked.connect(toggleCalibration)
        
def updatePlot():
    global xRaw, yRaw, zRaw, xCal, yCal, zCal, x, y ,z
    if ser.in_waiting > 0:
        try:
            line= ser.readline().decode('utf-8').strip()
            values = line.split(',')
            if len(values)==3:
                x = x*.75 + float(values[0])*.25
                y = y*.75 + float(values[1])*.25
                z = z*.75 + float(values[2])*.25
                if not calibrated:
                    xRaw =np.append(xRaw, x)[-maxPoints:]
                    yRaw =np.append(yRaw, y)[-maxPoints:]
                    zRaw =np.append(zRaw, z)[-maxPoints:]
                    xyScatter.setData(x=xRaw, y=yRaw, brush=pg.mkBrush(0,0,255,255))
                    yzScatter.setData(x=yRaw, y=zRaw, brush=pg.mkBrush(0,255,0,255))
                    xzScatter.setData(x=xRaw, y=zRaw, brush=pg.mkBrush(255,0,0,255))
                    
                    if len(xRaw)>10:
                        minVals = np.min(np.column_stack((xRaw,yRaw,zRaw)),axis=0)
                        maxVals = np.max(np.column_stack((xRaw,yRaw,zRaw)),axis=0)
                        
                        minMaxLabel.setStyleSheet("color: red; font-weight: bold; font-size: 16px;")
                        minMaxLabel.setText("Min(x,y,z: "+str(minVals.round(2))+" Max(x,y,z): "
                            +str(maxVals.round(2)))
                
                if calibrated:
                    xC= (x - offsets[0])*scales[0]
                    yC= (y - offsets[1])*scales[1]
                    zC= (z - offsets[2])*scales[2]
                    
                    xCal = np.append(xCal, xC)[-maxPoints:]
                    yCal = np.append(yCal, yC)[-maxPoints:]
                    zCal = np.append(zCal, zC)[-maxPoints:]
                    
                    xyScatter.setData(x=xCal, y=yCal, brush=pg.mkBrush(0,0,255,120))
                    yzScatter.setData(x=yCal, y=zCal, brush=pg.mkBrush(0,255,0,120))
                    xzScatter.setData(x=xCal, y=zCal, brush=pg.mkBrush(255,0,0,120))
                    
                    headRad= math.atan2(yC,xC)
                    headDeg=(headRad*360/2/math.pi)%360
                    compassRad= -headRad+ math.pi/2
                    compassDeg = (-headDeg + 90)%360
                    xDot=1.5*math.cos(compassRad)
                    yDot=1.5*math.sin(compassRad)
                    dot.setData(pos=([(xDot,yDot)]))
                    arrowShaft.setData(x=[0,xDot],y=[0,yDot])
                    liveHeading.setText("Heading: "+str(int(headDeg))+"\u00B0")      
        except Exception as e:
            print("Parse Error: ", e)

plotTimer =QtCore.QTimer()
plotTimer.timeout.connect(updatePlot)
plotTimer.start(50)
mainWindow.show()
try:
    app.exec_()
finally:
    ser.close()

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import serial

import numpy as np

from PyQt5 import QtWidgets, QtCore, QtGui

import pyqtgraph as pg

import math

serialPort = 'COM8'

baudRate =115200

to =.1

ser =serial.Serial(serialPort, baudRate, timeout=to)

maxPoints = 2000

xRaw = np.empty(0)

yRaw = np.empty(0)

zRaw = np.empty(0)

xCal = np.empty(0)

yCal = np.empty(0)

zCal = np.empty(0)

x=0

y=0

z=0

calibrated = False

offsets = np.zeros(3)

scales = np.ones(3)

app = QtWidgets.QApplication([])

mainWindow = QtWidgets.QWidget()

mainWindow.setWindowTitle("Magnetometer Calibratioin")

mainLayout =QtWidgets.QVBoxLayout()

mainWindow.setLayout(mainLayout)

statusLabel = QtWidgets.QLabel("Program Running: Not Calibrated")

statusLabel.setAlignment(QtCore.Qt.AlignCenter)

statusLabel.setStyleSheet("color: green; font-weight: bold; font-size: 20px;")

mainLayout.addWidget(statusLabel)

minMaxLabel=QtWidgets.QLabel("Min/Max: N/A")

minMaxLabel.setAlignment(QtCore.Qt.AlignCenter)

minMaxLabel.setStyleSheet("color: green; font-weight: bold; font-size: 16px;")

mainLayout.addWidget(minMaxLabel)

calibrateButton = QtWidgets.QPushButton("Start Calibration")

calibrateButton.setCheckable(True)

mainLayout.addWidget(calibrateButton)

plotLayout =QtWidgets.QGridLayout()

mainLayout.addLayout(plotLayout)

xyPlot = pg.PlotWidget(title="XY Plane")

yzPlot = pg.PlotWidget(title="YZ Plane")

xzPlot = pg.PlotWidget(title="XZ Plane")

for plot in [xyPlot, yzPlot, xzPlot]:

plot.setAspectLocked(True)

plot.showGrid(x=True, y=True)

plot.setMinimumSize(300,300)

plotLayout.addWidget(xyPlot, 0,0)

plotLayout.addWidget(yzPlot, 0,1)

plotLayout.addWidget(xzPlot, 1,0)

xyScatter = pg.ScatterPlotItem(size=5)

yzScatter = pg.ScatterPlotItem(size=5)

xzScatter = pg.ScatterPlotItem(size=5)

xyPlot.addItem(xyScatter)

yzPlot.addItem(yzScatter)

xzPlot.addItem(xzScatter)

headingPlot = pg.PlotWidget(title="Compass Heading")

headingPlot.setAspectLocked(True)

headingPlot.showGrid(x=True, y=True)

headingPlot.setMinimumSize(300,300)

headingPlot.hideAxis('left')

headingPlot.hideAxis('bottom')

plotLayout.addWidget(headingPlot,1,1)

compassCircle=pg.EllipseROI([-1.5,-1.5],[3.,3.],pen=pg.mkPen('b',width=4),movable=False, resizable=False)

headingPlot.addItem(compassCircle)

compassCircle.removeHandle(0)

compassCircle.setZValue(0)

arrowShaft=pg.PlotCurveItem( x=[0,0],y=[0,1.5],pen=pg.mkPen('r',width=4))

headingPlot.addItem(arrowShaft)

dot=pg.ScatterPlotItem(pos=[(0,1.5)],width=4,size=10,pen=pg.mkPen('y'),brush=pg.mkBrush('y'))

dot.setZValue(1)

headingPlot.addItem(dot)

for angle, label in zip([0,90,180,270],['E','N','W','S']):

rad = angle/360*2*math.pi

xPos = np.cos(rad)*1.8

yPos = np.sin(rad)*1.8

text=pg.TextItem(label, anchor = (.5,.5), color='g')

font=QtGui.QFont()

font.setBold(True)

font.setPointSize(12)

text.setFont(font)

text.setPos(xPos,yPos)

headingPlot.addItem(text)

liveHeading = pg.TextItem("Heading: 0.0\u00B0",anchor= (.5,.5),color='w')

liveHeading.setFont(font)

liveHeading.setPos(0,-2.2)

liveHeading.setZValue(1)

headingPlot.addItem(liveHeading)

def toggleCalibration():

global calibrated, xRaw, yRaw, zRaw, xCal, yCal, zCal, offsets, scales

if calibrateButton.isChecked():

calibrateButton.setText("Stop Calibration")

statusLabel.setText("Mode: Calibration")

statusLabel.setStyleSheet("color: red; font-weight: bold; font-size: 20px;")

minMaxLabel.setText("Min/Max: collecting . . .")

minMaxLabel.setStyleSheet("color: red; font-weight: bold; font-size: 16px;")

calibrated = False

xRaw = np.empty(0)

yRaw = np.empty(0)

zRaw = np.empty(0)

if not calibrateButton.isChecked():

calibrateButton.setText("Start Calibration")

statusLabel.setText("Mode: Calibrated")

statusLabel.setStyleSheet("color: green; font-weight: bold; font-size: 20px;")

rawData = np.column_stack((xRaw,yRaw,zRaw))

minVals = np.min(rawData, axis=0)

maxVals = np.max(rawData, axis=0)

offsets = (maxVals + minVals)/2

scales = 2.0/(maxVals-minVals)

minMaxLabel.setStyleSheet("color: green; font-weight: bold; font-size: 16px;")

minMaxLabel.setText("Min(x,y,z: "+str(minVals.round(2))+" Max(x,y,z): "

+str(maxVals.round(2))+" Offsets(x,y,z): "+str(offsets.round(2))

+"Scales(x,y,z): "+str(scales.round(5)))

print("Calibration Completed.")

print("Offsets: ", offsets)

print("Scales: ", scales)

xCal = np.empty(0)

yCal = np.empty(0)

zCal = np.empty(0)

calibrated = True

calibrateButton.clicked.connect(toggleCalibration)

def updatePlot():

global xRaw, yRaw, zRaw, xCal, yCal, zCal, x, y ,z

if ser.in_waiting > 0:

try:

line= ser.readline().decode('utf-8').strip()

values = line.split(',')

if len(values)==3:

x = x*.75 + float(values[0])*.25

y = y*.75 + float(values[1])*.25

z = z*.75 + float(values[2])*.25

if not calibrated:

xRaw =np.append(xRaw, x)[-maxPoints:]

yRaw =np.append(yRaw, y)[-maxPoints:]

zRaw =np.append(zRaw, z)[-maxPoints:]

xyScatter.setData(x=xRaw, y=yRaw, brush=pg.mkBrush(0,0,255,255))

yzScatter.setData(x=yRaw, y=zRaw, brush=pg.mkBrush(0,255,0,255))

xzScatter.setData(x=xRaw, y=zRaw, brush=pg.mkBrush(255,0,0,255))

if len(xRaw)>10:

minVals = np.min(np.column_stack((xRaw,yRaw,zRaw)),axis=0)

maxVals = np.max(np.column_stack((xRaw,yRaw,zRaw)),axis=0)

minMaxLabel.setStyleSheet("color: red; font-weight: bold; font-size: 16px;")

minMaxLabel.setText("Min(x,y,z: "+str(minVals.round(2))+" Max(x,y,z): "

+str(maxVals.round(2)))

if calibrated:

xC= (x - offsets[0])*scales[0]

yC= (y - offsets[1])*scales[1]

zC= (z - offsets[2])*scales[2]

xCal = np.append(xCal, xC)[-maxPoints:]

yCal = np.append(yCal, yC)[-maxPoints:]

zCal = np.append(zCal, zC)[-maxPoints:]

xyScatter.setData(x=xCal, y=yCal, brush=pg.mkBrush(0,0,255,120))

yzScatter.setData(x=yCal, y=zCal, brush=pg.mkBrush(0,255,0,120))

xzScatter.setData(x=xCal, y=zCal, brush=pg.mkBrush(255,0,0,120))

headRad= math.atan2(yC,xC)

headDeg=(headRad*360/2/math.pi)%360

compassRad= -headRad+ math.pi/2

compassDeg = (-headDeg + 90)%360

xDot=1.5*math.cos(compassRad)

yDot=1.5*math.sin(compassRad)

dot.setData(pos=([(xDot,yDot)]))

arrowShaft.setData(x=[0,xDot],y=[0,yDot])

liveHeading.setText("Heading: "+str(int(headDeg))+"\u00B0")

except Exception as e:

print("Parse Error: ", e)

plotTimer =QtCore.QTimer()

plotTimer.timeout.connect(updatePlot)

plotTimer.start(50)

mainWindow.show()

try:

app.exec_()

finally:

ser.close()

Arduino, Python

Calibrated Compass Display in Python and PyQt5

October 15, 2025 admin

In this video lesson we develop a Graphical Digital Compass using python and PyQt5. The data comes from a QMC5883L magnetometer connected to an arduino. The magnetometer is on the GY-87 IMU module. The arduino sends the raw data to python. With the raw data in Python, we then calibrate the sensor, and create a graphical representation of a digital compass. The circuit schematic we are using is:

The simple program for collecting the raw data on Arduino is:

#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>
#include <Wire.h>
#include <QMC5883LCompass.h>
int x,y,z;
Adafruit_MPU6050 mpu;
QMC5883LCompass compass;
void setup() {
Serial.begin(115200);
mpu.begin();
mpu.setI2CBypass(true);
compass.init();
}
void loop() {
 compass.read();
 x = compass.getX();
 y = compass.getY();
 z = compass.getZ();
Serial.print(x);
Serial.print(',');
Serial.print(y);
Serial.print(',');
Serial.println(z);
 delay(100);
}

#include <Adafruit_MPU6050.h>

#include <Adafruit_Sensor.h>

#include <Wire.h>

#include <QMC5883LCompass.h>

int x,y,z;

Adafruit_MPU6050 mpu;

QMC5883LCompass compass;

void setup() {

Serial.begin(115200);

mpu.begin();

mpu.setI2CBypass(true);

compass.init();

}

void loop() {

compass.read();

x = compass.getX();

y = compass.getY();

z = compass.getZ();

Serial.print(x);

Serial.print(',');

Serial.print(y);

Serial.print(',');

Serial.println(z);

delay(100);

}

On the python side, this is the code we developed which both calibrates the magnetometers, and displays a Digital Compass.

import serial
import numpy as np
from PyQt5 import QtWidgets, QtCore, QtGui
import pyqtgraph as pg
import math
serialPort = 'COM8'
baudRate =115200
to =.1
ser =serial.Serial(serialPort, baudRate, timeout=to)
maxPoints = 2000
xRaw = np.empty(0)
yRaw = np.empty(0)
zRaw = np.empty(0)

xCal = np.empty(0)
yCal = np.empty(0)
zCal = np.empty(0)
x=0
y=0
z=0

calibrated = False
offsets = np.zeros(3)
scales = np.ones(3)

app = QtWidgets.QApplication([])
mainWindow = QtWidgets.QWidget()
mainWindow.setWindowTitle("Magnetometer Calibratioin")
mainLayout =QtWidgets.QVBoxLayout()
mainWindow.setLayout(mainLayout)

statusLabel = QtWidgets.QLabel("Program Running: Not Calibrated")
statusLabel.setAlignment(QtCore.Qt.AlignCenter)
statusLabel.setStyleSheet("color: green; font-weight: bold; font-size: 20px;")
mainLayout.addWidget(statusLabel)

minMaxLabel=QtWidgets.QLabel("Min/Max: N/A")
minMaxLabel.setAlignment(QtCore.Qt.AlignCenter)
minMaxLabel.setStyleSheet("color: green; font-weight: bold; font-size: 16px;")
mainLayout.addWidget(minMaxLabel)

calibrateButton = QtWidgets.QPushButton("Start Calibration")
calibrateButton.setCheckable(True)
mainLayout.addWidget(calibrateButton)


plotLayout =QtWidgets.QGridLayout()
mainLayout.addLayout(plotLayout)
xyPlot = pg.PlotWidget(title="XY Plane")
yzPlot = pg.PlotWidget(title="YZ Plane")
xzPlot = pg.PlotWidget(title="XZ Plane")
for plot in [xyPlot, yzPlot, xzPlot]:
    plot.setAspectLocked(True)
    plot.showGrid(x=True, y=True)
    plot.setMinimumSize(300,300)
plotLayout.addWidget(xyPlot, 0,0)
plotLayout.addWidget(yzPlot, 0,1)
plotLayout.addWidget(xzPlot, 1,0)

xyScatter = pg.ScatterPlotItem(size=5)
yzScatter = pg.ScatterPlotItem(size=5)
xzScatter = pg.ScatterPlotItem(size=5)

xyPlot.addItem(xyScatter)
yzPlot.addItem(yzScatter)
xzPlot.addItem(xzScatter)

headingPlot = pg.PlotWidget(title="Compass Heading")
headingPlot.setAspectLocked(True)
headingPlot.showGrid(x=True, y=True)
headingPlot.setMinimumSize(300,300)
headingPlot.hideAxis('left')
headingPlot.hideAxis('bottom')
plotLayout.addWidget(headingPlot,1,1)

compassCircle=pg.EllipseROI([-1.5,-1.5],[3.,3.],pen=pg.mkPen('b',width=4),movable=False, resizable=False)
headingPlot.addItem(compassCircle)
compassCircle.removeHandle(0)
compassCircle.removeHandle(0)
compassCircle.setZValue(0)

arrowShaft=pg.PlotCurveItem( x=[0,0],y=[0,1.5],pen=pg.mkPen('r',width=4))
headingPlot.addItem(arrowShaft)
dot=pg.ScatterPlotItem(pos=[(0,1.5)],width=4,size=10,pen=pg.mkPen('y'),brush=pg.mkBrush('y'))
dot.setZValue(1)
headingPlot.addItem(dot)

for angle, label in zip([0,90,180,270],['E','N','W','S']):
    rad = angle/360*2*math.pi
    xPos = np.cos(rad)*1.8
    yPos = np.sin(rad)*1.8
    text=pg.TextItem(label, anchor = (.5,.5), color='g')
    font=QtGui.QFont()
    font.setBold(True)
    font.setPointSize(12)
    text.setFont(font)
    text.setPos(xPos,yPos)
    headingPlot.addItem(text)
    
liveHeading = pg.TextItem("Heading: 0.0\u00B0",anchor= (.5,.5),color='w')
liveHeading.setFont(font)
liveHeading.setPos(0,-2.2)
liveHeading.setZValue(1)
headingPlot.addItem(liveHeading)


def toggleCalibration():
    global calibrated, xRaw, yRaw, zRaw, xCal, yCal, zCal, offsets, scales
    
    if calibrateButton.isChecked():
        calibrateButton.setText("Stop Calibration")
        statusLabel.setText("Mode: Calibration")
        statusLabel.setStyleSheet("color: red; font-weight: bold; font-size: 20px;")
        minMaxLabel.setText("Min/Max: collecting . . .")
        minMaxLabel.setStyleSheet("color: red; font-weight: bold; font-size: 16px;")
        calibrated = False
        xRaw = np.empty(0)
        yRaw = np.empty(0)
        zRaw = np.empty(0)
    if not calibrateButton.isChecked():
        calibrateButton.setText("Start Calibration")
        statusLabel.setText("Mode: Calibrated")
        statusLabel.setStyleSheet("color: green; font-weight: bold; font-size: 20px;")
        
        rawData = np.column_stack((xRaw,yRaw,zRaw))
        minVals = np.min(rawData, axis=0)
        maxVals = np.max(rawData, axis=0)
        offsets = (maxVals + minVals)/2
        scales = 2.0/(maxVals-minVals)
        minMaxLabel.setStyleSheet("color: green; font-weight: bold; font-size: 16px;")
        minMaxLabel.setText("Min(x,y,z: "+str(minVals.round(2))+" Max(x,y,z): "
                            +str(maxVals.round(2))+" Offsets(x,y,z): "+str(offsets.round(2))
                            +"Scales(x,y,z): "+str(scales.round(5)))
        print("Calibration Completed.")
        print("Offsets: ", offsets)
        print("Scales: ", scales)
        
        xCal = np.empty(0)
        yCal = np.empty(0)
        zCal = np.empty(0)
        calibrated = True

calibrateButton.clicked.connect(toggleCalibration)
        
def updatePlot():
    global xRaw, yRaw, zRaw, xCal, yCal, zCal
    if ser.in_waiting > 0:
        try:
            line= ser.readline().decode('utf-8').strip()
            values = line.split(',')
            if len(values)==3:
                x = float(values[0])
                y = float(values[1])
                z = float(values[2])
                if not calibrated:
                    xRaw =np.append(xRaw, x)[-maxPoints:]
                    yRaw =np.append(yRaw, y)[-maxPoints:]
                    zRaw =np.append(zRaw, z)[-maxPoints:]
                    xyScatter.setData(x=xRaw, y=yRaw, brush=pg.mkBrush(0,0,255,255))
                    yzScatter.setData(x=yRaw, y=zRaw, brush=pg.mkBrush(0,255,0,255))
                    xzScatter.setData(x=xRaw, y=zRaw, brush=pg.mkBrush(255,0,0,255))
                    
                    if len(xRaw)>10:
                        minVals = np.min(np.column_stack((xRaw,yRaw,zRaw)),axis=0)
                        maxVals = np.max(np.column_stack((xRaw,yRaw,zRaw)),axis=0)
                        
                        minMaxLabel.setStyleSheet("color: red; font-weight: bold; font-size: 16px;")
                        minMaxLabel.setText("Min(x,y,z: "+str(minVals.round(2))+" Max(x,y,z): "
                            +str(maxVals.round(2)))
                
                if calibrated:
                    xC= (x - offsets[0])*scales[0]
                    yC= (y - offsets[1])*scales[1]
                    zC= (z - offsets[2])*scales[2]
                    
                    xCal = np.append(xCal, xC)[-maxPoints:]
                    yCal = np.append(yCal, yC)[-maxPoints:]
                    zCal = np.append(zCal, zC)[-maxPoints:]
                    
                    xyScatter.setData(x=xCal, y=yCal, brush=pg.mkBrush(0,0,255,120))
                    yzScatter.setData(x=yCal, y=zCal, brush=pg.mkBrush(0,255,0,120))
                    xzScatter.setData(x=xCal, y=zCal, brush=pg.mkBrush(255,0,0,120))
                    
                    headRad=math.atan2(yC,xC)
                    headDeg=(headRad*360/2/math.pi)%360
                    compassRad= -headRad+ math.pi/2
                    compassDeg = (-headDeg + 90)%360
                    xDot=1.5*math.cos(compassRad)
                    yDot=1.5*math.sin(compassRad)
                    dot.setData(pos=([(xDot,yDot)]))
                    arrowShaft.setData(x=[0,xDot],y=[0,yDot])
                    liveHeading.setText("Heading: "+str(int(headDeg))+"\u00B0")
                    
                    
        
        except Exception as e:
            print("Parse Error: ", e)

plotTimer =QtCore.QTimer()
plotTimer.timeout.connect(updatePlot)
plotTimer.start(50)
mainWindow.show()
try:
    app.exec_()
finally:
    ser.close()

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import serial

import numpy as np

from PyQt5 import QtWidgets, QtCore, QtGui

import pyqtgraph as pg

import math

serialPort = 'COM8'

baudRate =115200

to =.1

ser =serial.Serial(serialPort, baudRate, timeout=to)

maxPoints = 2000

xRaw = np.empty(0)

yRaw = np.empty(0)

zRaw = np.empty(0)

xCal = np.empty(0)

yCal = np.empty(0)

zCal = np.empty(0)

x=0

y=0

z=0

calibrated = False

offsets = np.zeros(3)

scales = np.ones(3)

app = QtWidgets.QApplication([])

mainWindow = QtWidgets.QWidget()

mainWindow.setWindowTitle("Magnetometer Calibratioin")

mainLayout =QtWidgets.QVBoxLayout()

mainWindow.setLayout(mainLayout)

statusLabel = QtWidgets.QLabel("Program Running: Not Calibrated")

statusLabel.setAlignment(QtCore.Qt.AlignCenter)

statusLabel.setStyleSheet("color: green; font-weight: bold; font-size: 20px;")

mainLayout.addWidget(statusLabel)

minMaxLabel=QtWidgets.QLabel("Min/Max: N/A")

minMaxLabel.setAlignment(QtCore.Qt.AlignCenter)

minMaxLabel.setStyleSheet("color: green; font-weight: bold; font-size: 16px;")

mainLayout.addWidget(minMaxLabel)

calibrateButton = QtWidgets.QPushButton("Start Calibration")

calibrateButton.setCheckable(True)

mainLayout.addWidget(calibrateButton)

plotLayout =QtWidgets.QGridLayout()

mainLayout.addLayout(plotLayout)

xyPlot = pg.PlotWidget(title="XY Plane")

yzPlot = pg.PlotWidget(title="YZ Plane")

xzPlot = pg.PlotWidget(title="XZ Plane")

for plot in [xyPlot, yzPlot, xzPlot]:

plot.setAspectLocked(True)

plot.showGrid(x=True, y=True)

plot.setMinimumSize(300,300)

plotLayout.addWidget(xyPlot, 0,0)

plotLayout.addWidget(yzPlot, 0,1)

plotLayout.addWidget(xzPlot, 1,0)

xyScatter = pg.ScatterPlotItem(size=5)

yzScatter = pg.ScatterPlotItem(size=5)

xzScatter = pg.ScatterPlotItem(size=5)

xyPlot.addItem(xyScatter)

yzPlot.addItem(yzScatter)

xzPlot.addItem(xzScatter)

headingPlot = pg.PlotWidget(title="Compass Heading")

headingPlot.setAspectLocked(True)

headingPlot.showGrid(x=True, y=True)

headingPlot.setMinimumSize(300,300)

headingPlot.hideAxis('left')

headingPlot.hideAxis('bottom')

plotLayout.addWidget(headingPlot,1,1)

compassCircle=pg.EllipseROI([-1.5,-1.5],[3.,3.],pen=pg.mkPen('b',width=4),movable=False, resizable=False)

headingPlot.addItem(compassCircle)

compassCircle.removeHandle(0)

compassCircle.setZValue(0)

arrowShaft=pg.PlotCurveItem( x=[0,0],y=[0,1.5],pen=pg.mkPen('r',width=4))

headingPlot.addItem(arrowShaft)

dot=pg.ScatterPlotItem(pos=[(0,1.5)],width=4,size=10,pen=pg.mkPen('y'),brush=pg.mkBrush('y'))

dot.setZValue(1)

headingPlot.addItem(dot)

for angle, label in zip([0,90,180,270],['E','N','W','S']):

rad = angle/360*2*math.pi

xPos = np.cos(rad)*1.8

yPos = np.sin(rad)*1.8

text=pg.TextItem(label, anchor = (.5,.5), color='g')

font=QtGui.QFont()

font.setBold(True)

font.setPointSize(12)

text.setFont(font)

text.setPos(xPos,yPos)

headingPlot.addItem(text)

liveHeading = pg.TextItem("Heading: 0.0\u00B0",anchor= (.5,.5),color='w')

liveHeading.setFont(font)

liveHeading.setPos(0,-2.2)

liveHeading.setZValue(1)

headingPlot.addItem(liveHeading)

def toggleCalibration():

global calibrated, xRaw, yRaw, zRaw, xCal, yCal, zCal, offsets, scales

if calibrateButton.isChecked():

calibrateButton.setText("Stop Calibration")

statusLabel.setText("Mode: Calibration")

statusLabel.setStyleSheet("color: red; font-weight: bold; font-size: 20px;")

minMaxLabel.setText("Min/Max: collecting . . .")

minMaxLabel.setStyleSheet("color: red; font-weight: bold; font-size: 16px;")

calibrated = False

xRaw = np.empty(0)

yRaw = np.empty(0)

zRaw = np.empty(0)

if not calibrateButton.isChecked():

calibrateButton.setText("Start Calibration")

statusLabel.setText("Mode: Calibrated")

statusLabel.setStyleSheet("color: green; font-weight: bold; font-size: 20px;")

rawData = np.column_stack((xRaw,yRaw,zRaw))

minVals = np.min(rawData, axis=0)

maxVals = np.max(rawData, axis=0)

offsets = (maxVals + minVals)/2

scales = 2.0/(maxVals-minVals)

minMaxLabel.setStyleSheet("color: green; font-weight: bold; font-size: 16px;")

minMaxLabel.setText("Min(x,y,z: "+str(minVals.round(2))+" Max(x,y,z): "

+str(maxVals.round(2))+" Offsets(x,y,z): "+str(offsets.round(2))

+"Scales(x,y,z): "+str(scales.round(5)))

print("Calibration Completed.")

print("Offsets: ", offsets)

print("Scales: ", scales)

xCal = np.empty(0)

yCal = np.empty(0)

zCal = np.empty(0)

calibrated = True

calibrateButton.clicked.connect(toggleCalibration)

def updatePlot():

global xRaw, yRaw, zRaw, xCal, yCal, zCal

if ser.in_waiting > 0:

try:

line= ser.readline().decode('utf-8').strip()

values = line.split(',')

if len(values)==3:

x = float(values[0])

y = float(values[1])

z = float(values[2])

if not calibrated:

xRaw =np.append(xRaw, x)[-maxPoints:]

yRaw =np.append(yRaw, y)[-maxPoints:]

zRaw =np.append(zRaw, z)[-maxPoints:]

xyScatter.setData(x=xRaw, y=yRaw, brush=pg.mkBrush(0,0,255,255))

yzScatter.setData(x=yRaw, y=zRaw, brush=pg.mkBrush(0,255,0,255))

xzScatter.setData(x=xRaw, y=zRaw, brush=pg.mkBrush(255,0,0,255))

if len(xRaw)>10:

minVals = np.min(np.column_stack((xRaw,yRaw,zRaw)),axis=0)

maxVals = np.max(np.column_stack((xRaw,yRaw,zRaw)),axis=0)

minMaxLabel.setStyleSheet("color: red; font-weight: bold; font-size: 16px;")

minMaxLabel.setText("Min(x,y,z: "+str(minVals.round(2))+" Max(x,y,z): "

+str(maxVals.round(2)))

if calibrated:

xC= (x - offsets[0])*scales[0]

yC= (y - offsets[1])*scales[1]

zC= (z - offsets[2])*scales[2]

xCal = np.append(xCal, xC)[-maxPoints:]

yCal = np.append(yCal, yC)[-maxPoints:]

zCal = np.append(zCal, zC)[-maxPoints:]

xyScatter.setData(x=xCal, y=yCal, brush=pg.mkBrush(0,0,255,120))

yzScatter.setData(x=yCal, y=zCal, brush=pg.mkBrush(0,255,0,120))

xzScatter.setData(x=xCal, y=zCal, brush=pg.mkBrush(255,0,0,120))

headRad=math.atan2(yC,xC)

headDeg=(headRad*360/2/math.pi)%360

compassRad= -headRad+ math.pi/2

compassDeg = (-headDeg + 90)%360

xDot=1.5*math.cos(compassRad)

yDot=1.5*math.sin(compassRad)

dot.setData(pos=([(xDot,yDot)]))

arrowShaft.setData(x=[0,xDot],y=[0,yDot])

liveHeading.setText("Heading: "+str(int(headDeg))+"\u00B0")

except Exception as e:

print("Parse Error: ", e)

plotTimer =QtCore.QTimer()

plotTimer.timeout.connect(updatePlot)

plotTimer.start(50)

mainWindow.show()

try:

app.exec_()

finally:

ser.close()

Arduino

Calibrating a 3-Axis Magnetometer

September 20, 2025 admin

In this video lesson we show you how to calibrate the QMC5883L 3-axis magnetometer. The lesson is geared toward this specific magnetometer, but the procedure will be the same for any 3-axis magnetometer. We then use the calibrated reading to measure and calculate the magnetic heading of the device. With this, we have created a calibrated digital compass. In this lesson we are using the GY-87 module, which contains the QMC5883L magnetometer. We are connecting the module to the arduino using the following schematic:

In the video we develop two programs. The first program determines your sensor’s calibration constants. Then the second program uses those calibration constants to calculate heading, or yaw. The second program uses the offsets and scale parameters for MY PARTICULAR SENSOR. These values were determined using the first program. You must determine these values for your sensor, and then edit the second program to use your particular calibration parameters.

Program to determine your calibration parameters:

#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>
#include <Wire.h>
#include <QMC5883LCompass.h>
int x, y, z;
int xMax = -10000;
int xMin = 10000;
int yMax = -10000;
int yMin = 10000;
int zMax = -10000;
int zMin = 10000;
float xOffset, xScale, yOffset, yScale, zOffset, zScale;
Adafruit_MPU6050 mpu;
QMC5883LCompass compass;
void setup() {
  Serial.begin(115200);
  mpu.begin();
  mpu.setI2CBypass(true);
  compass.init();
}
void loop() {
  compass.read();
  x = compass.getX();
  y = compass.getY();
  z = compass.getZ();
  if (x > xMax) {
    xMax = x;
  }
  if (x < xMin) {
    xMin = x;
  }
  if (y>yMax){
    yMax=y;
  }
  if (y<yMin){
    yMin=y;
  }
  if (z > zMax) {
    zMax = z;
  }
  if (z < zMin) {
    zMin = z;
  }
  xOffset = (xMax + xMin) / 2.;
  yOffset = (yMax + yMin) / 2.;
  zOffset = (zMax + zMin) / 2.;
  xScale = 2. / (xMax - xMin);
  yScale = 2. / (yMax - yMin);
  zScale = 2. / (zMax - zMin);
  Serial.print(x);
  Serial.print(',');
  Serial.print(y);
  Serial.print(',');
  Serial.print(z);
    Serial.print(',');
  Serial.print(xMax);
  Serial.print(',');
  Serial.print(xMin);
  Serial.print(',');
  Serial.print(yMax);
  Serial.print(',');
  Serial.print(yMin);
  Serial.print(',');
  Serial.print(zMax);
  Serial.print(',');
  Serial.print(zMin);
  Serial.print(',');
  Serial.print(xOffset);
  Serial.print(',');
  Serial.print(yOffset);
  Serial.print(',');
  Serial.print(zOffset);
  Serial.print(',');
  Serial.print(xScale,5);
  Serial.print(',');
  Serial.print(yScale,5);
  Serial.print(',');
  Serial.println(zScale,5);
  delay(100);
}

#include <Adafruit_MPU6050.h>

#include <Adafruit_Sensor.h>

#include <Wire.h>

#include <QMC5883LCompass.h>

int x, y, z;

int xMax = -10000;

int xMin = 10000;

int yMax = -10000;

int yMin = 10000;

int zMax = -10000;

int zMin = 10000;

float xOffset, xScale, yOffset, yScale, zOffset, zScale;

Adafruit_MPU6050 mpu;

QMC5883LCompass compass;

void setup() {

Serial.begin(115200);

mpu.begin();

mpu.setI2CBypass(true);

compass.init();

}

void loop() {

compass.read();

x = compass.getX();

y = compass.getY();

z = compass.getZ();

if (x > xMax) {

xMax = x;

}

if (x < xMin) {

xMin = x;

}

if (y>yMax){

yMax=y;

}

if (y<yMin){

yMin=y;

}

if (z > zMax) {

zMax = z;

}

if (z < zMin) {

zMin = z;

}

xOffset = (xMax + xMin) / 2.;

yOffset = (yMax + yMin) / 2.;

zOffset = (zMax + zMin) / 2.;

xScale = 2. / (xMax - xMin);

yScale = 2. / (yMax - yMin);

zScale = 2. / (zMax - zMin);

Serial.print(x);

Serial.print(',');

Serial.print(y);

Serial.print(',');

Serial.print(z);

Serial.print(',');

Serial.print(xMax);

Serial.print(',');

Serial.print(xMin);

Serial.print(',');

Serial.print(yMax);

Serial.print(',');

Serial.print(yMin);

Serial.print(',');

Serial.print(zMax);

Serial.print(',');

Serial.print(zMin);

Serial.print(',');

Serial.print(xOffset);

Serial.print(',');

Serial.print(yOffset);

Serial.print(',');

Serial.print(zOffset);

Serial.print(',');

Serial.print(xScale,5);

Serial.print(',');

Serial.print(yScale,5);

Serial.print(',');

Serial.println(zScale,5);

delay(100);

}

Once you get your calibration parameters, then put them into this program. This program will then calculate your compass heading:

#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>
#include <Wire.h>
#include <QMC5883LCompass.h>
float x,y,z;
//The following numbers are for my particular sensor. You need
//to edit the following lines to put in your sensor calibration
//numbers
float xOffset=-382.5;
float yOffset=378.5;
float zOffset=1014.5;
float xScale = .00121;
float yScale=.00115;
float zScale=.00105;
float head;

Adafruit_MPU6050 mpu;
QMC5883LCompass compass;
void setup() {
Serial.begin(115200);
mpu.begin();
mpu.setI2CBypass(true);
compass.init();
}
void loop() {
 compass.read();
 x = (compass.getX()-xOffset)*xScale;
 y = (compass.getY()-yOffset)*yScale;
 z = (compass.getZ()-zOffset)*zScale;

// Serial.print(x);
// Serial.print(',');
// Serial.print(y);
// Serial.print(',');
// Serial.println(z);
head = atan2(y,x)*360/2/PI;
Serial.print("Heading: ");
Serial.println(head);
 delay(100);
}

#include <Adafruit_MPU6050.h>

#include <Adafruit_Sensor.h>

#include <Wire.h>

#include <QMC5883LCompass.h>

float x,y,z;

//The following numbers are for my particular sensor. You need

//to edit the following lines to put in your sensor calibration

//numbers

float xOffset=-382.5;

float yOffset=378.5;

float zOffset=1014.5;

float xScale = .00121;

float yScale=.00115;

float zScale=.00105;

float head;

Adafruit_MPU6050 mpu;

QMC5883LCompass compass;

void setup() {

Serial.begin(115200);

mpu.begin();

mpu.setI2CBypass(true);

compass.init();

}

void loop() {

compass.read();

x = (compass.getX()-xOffset)*xScale;

y = (compass.getY()-yOffset)*yScale;

z = (compass.getZ()-zOffset)*zScale;

// Serial.print(x);

// Serial.print(',');

// Serial.print(y);

// Serial.print(',');

// Serial.println(z);

head = atan2(y,x)*360/2/PI;

Serial.print("Heading: ");

Serial.println(head);

delay(100);

}

Arduino

Using the QMC5883L Magnetometers on the GY-87 Module

September 17, 2025 admin

In this video lesson we activate the QMC5883L 3-axis magnetometer on our GY-87 module. We show how to read the raw magnetic field strength in the x, y, and z axis. Your homework assignment will be to then calibrate the measurements such that you center the measured values around 0, and create a unit circle. This calibration will be very similar to what we did for the accelerometers a few weeks ago. This is the schematic we continue to use in this lesson:

This is the code we developed in todays lesson to read the raw data from the magnetometers.

#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>
#include <Wire.h>
#include <QMC5883LCompass.h>
int x,y,z;
Adafruit_MPU6050 mpu;
QMC5883LCompass compass;
void setup() {
Serial.begin(115200);
mpu.begin();
mpu.setI2CBypass(true);
compass.init();
}
void loop() {
 compass.read();
 x = compass.getX();
 y = compass.getY();
 z = compass.getZ();
Serial.print(x);
Serial.print(',');
Serial.print(y);
Serial.print(',');
Serial.println(z);
 delay(100);
}

#include <Adafruit_MPU6050.h>

#include <Adafruit_Sensor.h>

#include <Wire.h>

#include <QMC5883LCompass.h>

int x,y,z;

Adafruit_MPU6050 mpu;

QMC5883LCompass compass;

void setup() {

Serial.begin(115200);

mpu.begin();

mpu.setI2CBypass(true);

compass.init();

}

void loop() {

compass.read();

x = compass.getX();

y = compass.getY();

z = compass.getZ();

Serial.print(x);

Serial.print(',');

Serial.print(y);

Serial.print(',');

Serial.println(z);

delay(100);

}

Technology Tutorials

Tag Archives: QMC5883L

Ultimate 9-axis Program for Easily and Accurately Calibrating a 9-axis IMU on Arduino

Improving Digital Compass Accuracy With a Low Pass Filter

Calibrated Compass Display in Python and PyQt5

Calibrating a 3-Axis Magnetometer

Using the QMC5883L Magnetometers on the GY-87 Module

Making The World a Better Place One High Tech Project at a Time. Enjoy!