April 12, 2025 On April 6, 2025

Heart Rate Monitor Kit with AD8232 ECG sensor module

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Ekostra Electronics

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AD8232 ECG Heart Rate Monitor Kit

Professional-Grade Biopotential Measurement for Arduino and Medical Applications

Introduction

The AD8232 ECG Sensor Module is a compact board that measures electrical activity of the heart. This single-lead ECG front end is designed for portable, low-power applications and works perfectly with Arduino for heart rate monitoring projects.

Key Features

❤️ Medical Grade

Single-lead ECG monitoring

📊 High Precision

Integrated signal conditioning

🔋 Low Power

170μA typical current consumption

⚡ Lead-Off Detection

Built-in electrode contact monitoring

Technical Specifications

Input Range	±1.5mV to ±100mV
Bandwidth	0.5Hz to 40Hz
Gain	100 V/V (adjustable)
Supply Voltage	3.0V to 5.5V
Output Type	Analog (ECG signal) + Digital (LO+/LO-)
Electrodes	3x Snap-on (RA, LA, RL)

Pin Configuration

Pin	Label	Description	Arduino Connection
1	3.3V	Power (3.3V recommended)	3.3V
2	GND	Ground	GND
3	OUTPUT	ECG Analog Output	A0
4	LO+	Lead-Off Detect Positive	D11 (Digital Input)
5	LO-	Lead-Off Detect Negative	D10(Digital Input)
6	SDN	Shutdown Control	D4 (Optional)

Important: Proper electrode placement is crucial for accurate readings

Electrode Placement

Standard Lead I Configuration:

RA (Right Arm): Right side of chest
LA (Left Arm): Left side of chest
RL (Right Leg): Ground reference

For best results, clean skin and use conductive gel

Basic ECG Monitoring

// AD8232 ECG Basic Monitoring
const int ecgPin = A0;
const int loPlus = 2;
const int loMinus = 3;

void setup() {
  Serial.begin(9600);
  pinMode(loPlus, INPUT);
  pinMode(loMinus, INPUT);
}

void loop() {
  if((digitalRead(loPlus) == 1 || (digitalRead(loMinus) == 1)){
    Serial.println("Electrode disconnected!");
  }
  else {
    int ecgValue = analogRead(ecgPin);
    Serial.println(ecgValue);
  }
  delay(10);
}

Processing Visualization: Use Serial Plotter or Processing IDE for ECG waveform display

Advanced Features

Heart Rate Calculation

// Detect R-peaks and calculate BPM
unsigned long lastBeat = 0;
float threshold = 520; // Adjust based on signal
float bpm = 0;

if(ecgValue > threshold && millis() > lastBeat + 200){
  bpm = 60000 / (millis() - lastBeat);
  lastBeat = millis();
  Serial.print("BPM: "); Serial.println(bpm);
}

Signal Filtering

// Simple moving average filter
#define FILTER_SIZE 5
int filterBuffer[FILTER_SIZE];
int filterIndex = 0;
int filteredValue = 0;

filterBuffer[filterIndex] = ecgValue;
filterIndex = (filterIndex + 1) % FILTER_SIZE;
for(int i=0; i<FILTER_SIZE; i++){
  filteredValue += filterBuffer[i];
}
filteredValue /= FILTER_SIZE;

SD Card Logging

// Log ECG data to SD card
#include 
#include 

File ecgFile;

void setup(){
  SD.begin(4); // CS pin
  ecgFile = SD.open("ecg.csv", FILE_WRITE);
}

void loop(){
  ecgFile.print(millis());
  ecgFile.print(",");
  ecgFile.println(ecgValue);
}

Bluetooth Streaming

// Stream ECG via Bluetooth
#include 

SoftwareSerial btSerial(10, 11); // RX, TX

void setup(){
  btSerial.begin(9600);
}

void loop(){
  btSerial.println(ecgValue);
  delay(10);
}