Heart rate monitor 2.0

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Kit purchase

Looking for parts? Check out our all-in-one kits below — packed with components, beginner-friendly guides, and tons of fun.

Name	Includes Arduino board	PURCHASE LINK
Elite Explorer Kit	Arduino Uno R4 WiFi	BUY
3 in 1 Ultimate Starter Kit	Arduino Uno R4 Minima	BUY

Course Introduction

This Arduino project builds a basic Heart Rate Monitor using the MAX30102 sensor and a 16x2 I2C LCD.

It detects heartbeats by analyzing infrared signals and calculates the heart rate in BPM.

The measured BPM is displayed on the LCD. A buzzer beeps with each beat, and an RGB LED indicates heart rate level—red for high, green for normal.

Note

If this is your first time working with an Arduino project, we recommend downloading and reviewing the basic materials first.

Required Components

In this project, we need the following components:

SN	COMPONENT INTRODUCTION	QUANTITY	PURCHASE LINK
1	Arduino UNO R4 Minima	1	BUY
2	USB Type-C cable	1
3	Breadboard	1	BUY
4	Wires	Several	BUY
5	I2C LCD 1602	1	BUY
6	Pulse Oximeter and Heart Rate Sensor Module (MAX30102)	1	BUY
7	RGB LED	1
8	Passive buzzer	1	BUY

Wiring

Common Connections:

Pulse Oximeter and Heart Rate Sensor Module (MAX30102)
- SDA: Connect to A4 on the Arduino.
- SCL: Connect to A5 on the Arduino.
- GND: Connect to breadboard’s negative power bus.
- VIN: Connect to breadboard’s red power bus.
I2C LCD 1602
- SDA: Connect to A4 on the Arduino.
- SCL: Connect to A5 on the Arduino.
- GND: Connect to breadboard’s negative power bus.
- VCC: Connect to breadboard’s red power bus.
RGB LED
- R: Connect to 6 on the Arduino.
- G: Connect to 5 on the Arduino.
- GND: Connect to breadboard’s negative power bus.
Passive Buzzer
- ＋: Connect to 9 on the Arduino.
- －: Connect to breadboard’s negative power bus.

Writing the Code

Note

You can copy this code into Arduino IDE.
To install the library, use the Arduino Library Manager and search for LiquidCrystal_I2C , MAX30105 and heartRate and install it.
Don’t forget to select the board(Arduino UNO R4 WIFI) and the correct port before clicking the Upload button.

#include <Wire.h>
#include "MAX30105.h"
#include "heartRate.h"
#include <LiquidCrystal_I2C.h>

#define BUZZER_PIN 9
#define RED_PIN 6      // Red pin of RGB LED
#define GREEN_PIN 5    // Green pin of RGB LED

MAX30105 particleSensor;
LiquidCrystal_I2C lcd(0x27, 16, 2);

int bpm = 0;
unsigned long lastDisplayTime = 0;

void setup() {
  Serial.begin(9600);
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(RED_PIN, OUTPUT);
  pinMode(GREEN_PIN, OUTPUT);

  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Initializing...");

  if (!particleSensor.begin(Wire, I2C_SPEED_STANDARD)) {
    Serial.println("MAX30102 not found");
    lcd.setCursor(0, 1);
    lcd.print("Sensor Error");
    while (1);
  }

  particleSensor.setup(); // Default configuration
  particleSensor.setPulseAmplitudeRed(0x0A);  // Red light for heart rate
  particleSensor.setPulseAmplitudeGreen(0);   // Turn off green light

  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Heart Monitor");
}

void loop() {
  const int NUM_READINGS = 100;
  long irValue;
  static uint32_t lastBeat = 0;

  for (int i = 0; i < NUM_READINGS; i++) {
    irValue = particleSensor.getIR();

    if (checkForBeat(irValue)) {
      uint32_t now = millis();
      int delta = now - lastBeat;
      lastBeat = now;

      bpm = 60000 / delta;

      Serial.print("BPM: ");
      Serial.println(bpm);

      lcd.setCursor(0, 1);
      lcd.print("BPM: ");
      lcd.print(bpm);
      lcd.print("   ");

      // Control RGB LED: light red or green
      if (bpm > 100) {
        digitalWrite(RED_PIN, HIGH);
        digitalWrite(GREEN_PIN, LOW);
      } else {
        digitalWrite(RED_PIN, LOW);
        digitalWrite(GREEN_PIN, HIGH);
      }

      // Beep once per heartbeat
      tone(BUZZER_PIN, 1000, 50); // 1kHz, 50ms
    }

    delay(10); // Sampling rate
  }
}