ECG Heart Monitor

In this advanced project, we’ll create a realistic heart rate monitor that displays ECG (electrocardiogram) waveforms on screen while controlling LED and buzzer for heartbeat simulation. This medical-style interface shows real-time heart rhythm patterns just like professional monitoring equipment!

Circuit

Sketch

// Pixel ECG Monitor – English version
import processing.io.*;

int ledPin   = 17;   // LED pin
int buzzPin  = 18;   // buzzer pin
float heartRate = 72; // beats per minute (BPM)
float time = 0;
ArrayList<Float> ecgWave = new ArrayList<Float>();
boolean beatFlag = false;
int lastBeat = 0;

void setup() {
    size(800, 400);
    GPIO.pinMode(ledPin,   GPIO.OUTPUT);
    GPIO.pinMode(buzzPin,  GPIO.OUTPUT);
    frameRate(60);
}

void draw() {
    background(20, 40, 20); // dark-medical green

    // generate ECG waveform
    generateECGWave();

    // draw medical grid
    drawMedicalGrid();

    // plot the waveform
    drawECGLine();

    // display numeric heart-rate
    displayHeartRate();

    // control LED & buzzer heartbeat
    controlHeartbeat();

    time += 0.02;
}

// medical grid background
void drawMedicalGrid() {
    stroke(0, 100, 0, 80); // soft green
    strokeWeight(1);

    // major grid (every 50 px)
    for (int x = 0; x < width; x += 50)  line(x, 0, x, height);
    for (int y = 0; y < height; y += 50) line(0, y, width, y);

    // minor grid (every 10 px)
    stroke(0, 60, 0, 40);
    for (int x = 0; x < width; x += 10)  line(x, 0, x, height);
    for (int y = 0; y < height; y += 10) line(0, y, width, y);
}

// plot the ECG trace
void drawECGLine() {
    if (ecgWave.size() > 1) {
        stroke(0, 255, 0); // bright green
        strokeWeight(2);
        noFill();
        beginShape();
        for (int i = 0; i < ecgWave.size(); i++) vertex(i, ecgWave.get(i));
        endShape();

        // scanning line effect
        stroke(0, 255, 0, 150);
        strokeWeight(1);
        line(ecgWave.size() - 1, 0, ecgWave.size() - 1, height);
    }
}

// show BPM value
void displayHeartRate() {
    // background panel
    fill(0, 0, 0, 120);
    noStroke();
    rect(width - 150, 20, 130, 80, 10);

    // labels
    fill(0, 255, 0);
    textAlign(CENTER);
    textSize(16);
    text("BPM", width - 85, 40);

    // number
    textSize(36);
    text(int(heartRate), width - 85, 75);

    // status indicator
    fill(heartRate > 100 ? color(255, 0, 0) : color(0, 255, 0));
    ellipse(width - 85, 90, 8, 8);
}

// drive LED & buzzer on every beat
void controlHeartbeat() {
    if (beatFlag) {
        GPIO.digitalWrite(ledPin, GPIO.HIGH);

        // short beep
        if (millis() - lastBeat < 100)  GPIO.digitalWrite(buzzPin, GPIO.HIGH);
        else                             GPIO.digitalWrite(buzzPin, GPIO.LOW);

        // heartbeat duration 200 ms
        if (millis() - lastBeat > 200) {
            beatFlag = false;
            GPIO.digitalWrite(ledPin,  GPIO.LOW);
            GPIO.digitalWrite(buzzPin, GPIO.LOW);
        }
    }
}

// create synthetic ECG data
void generateECGWave() {
    float beatInterval = 60.0 / heartRate; // seconds
    float pos = (time % beatInterval) / beatInterval;

    float val = 0;

    // P-wave (atrial depolarization)
    if (pos >= 0.05 && pos < 0.15) {
        float p = (pos - 0.05) / 0.1;
        val = 15 * sin(p * PI);
    }
    // QRS complex (ventricular depolarization)
    else if (pos >= 0.25 && pos < 0.35) {
        float qrs = (pos - 0.25) / 0.1;
        if      (qrs < 0.2)  val = -25 * sin(qrs * PI * 5);          // Q
        else if (qrs < 0.5)  val = 120 * sin((qrs - 0.2) * PI * 3.33); // R
        else                 val = -40 * sin((qrs - 0.5) * PI * 2);     // S

        // trigger beat on R-wave
        if (!beatFlag && qrs > 0.3) {
            beatFlag = true;
            lastBeat = millis();
        }
    }
    // T-wave (ventricular repolarization)
    else if (pos >= 0.55 && pos < 0.75) {
        float t = (pos - 0.55) / 0.2;
        val = 25 * sin(t * PI);
    }

    // baseline + small noise
    val += random(-2, 2);
    ecgWave.add(height / 2 - val);

    // keep trace within screen width
    if (ecgWave.size() > width) ecgWave.remove(0);
}

// keyboard controls for demo
void keyPressed() {
    if (key == '+' || key == '=') heartRate = min(heartRate + 5, 150);
    else if (key == '-')          heartRate = max(heartRate - 5, 40);
}

How it works?

This ECG heart monitor demonstrates sophisticated real-time data visualization and hardware control:

Medical ECG Simulation: - Authentic waveform generation: Creates realistic P-QRS-T wave patterns that match real electrocardiograms - P-wave: Represents atrial depolarization (heart chambers filling) - QRS complex: Shows ventricular depolarization (main heartbeat contraction) - T-wave: Indicates ventricular repolarization (heart muscle recovery) - Baseline noise: Adds realistic signal variations like real medical equipment

Professional Medical Interface: - Medical grid background: Dual-layer grid system (major/minor) like real ECG paper - Hospital-style colors: Dark green background with bright green trace - Real-time scanning line: Moving cursor effect simulating oscilloscope display - Digital readout: Large BPM display with status indicator (red for high, green for normal)

Real-time Data Processing: - Continuous waveform: Uses ArrayList<Float> to store scrolling ECG data - Timing calculations: Converts BPM to beat intervals using 60.0 / heartRate - Phase tracking: Monitors heartbeat cycle position to generate correct waveform shapes - Buffer management: Automatically removes old data points to maintain screen width

Hardware Integration: - LED heartbeat: Flashes LED on each R-wave peak (main heartbeat moment) - Audio feedback: Buzzer creates short beep sounds synchronized with heartbeat - Pulse timing: 200ms LED duration and 100ms buzzer beep for realistic timing - Beat detection: Triggers hardware only during R-wave peak for accuracy

Interactive Controls: - Adjustable heart rate: Press ‘+’ to increase BPM, ‘-’ to decrease - Rate limits: Constrained between 40-150 BPM for safety - Real-time updates: Changes immediately affect waveform speed and hardware timing

Advanced Programming Concepts: - State machines: Beat detection and hardware control states - Signal processing: Mathematical waveform generation using trigonometric functions - Real-time rendering: Smooth 60 FPS display updates - Hardware synchronization: Precise timing between visual and physical feedback - Medical accuracy: Waveform timing matches real cardiac cycles

Educational Value: - Medical knowledge: Learn about heart rhythm and ECG interpretation - Data visualization: Professional-grade real-time graphing techniques - Hardware control: Synchronized audio-visual feedback systems - Mathematical modeling: Sine wave combinations create complex realistic patterns

This project bridges the gap between digital simulation and real-world medical technology!

For more please refer to Processing Reference.