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Arduino Heart Rate Monitor Project

Introduction

The heart rate monitor is a crucial device for health monitoring, measuring heart rate in beats per minute (BPM). In this project, we will build a simple heart rate monitor using an Arduino and a pulse sensor. This guide will walk you through the entire process, from gathering materials to coding and testing the device.

Materials Required

  • Arduino Uno (or any compatible board)
    Arduino Uno
  • Pulse Sensor (e.g., Pulse Sensor Amped)
    Pulse Sensor
  • Breadboard
    Breadboard
  • Jumper Wires
    Jumper Wires
  • LED (optional)
    LED
  • Resistor (10k ohm)
  • 220-ohm Resistor (for the LED, optional)
  • USB Cable (for Arduino)
  • Arduino IDE (installed on your computer)

Circuit Diagram

Below is the circuit diagram illustrating how to connect the components:

Circuit Diagram

Pin Connections

Make the following connections between the components and the Arduino:

Component Connection
Pulse Sensor
  • VCC → 5V (Arduino)
  • GND → GND (Arduino)
  • Signal → A0 (Analog pin on Arduino)
LED (optional)
  • Anode (+) → Digital Pin 13 (Arduino)
  • Cathode (-) → 220-ohm Resistor → GND

Arduino Code

Copy and paste the following code into your Arduino IDE:


// Define the pin for the pulse sensor
const int pulsePin = A0; // Pulse Sensor is connected to analog pin A0
const int ledPin = 13;    // LED is connected to digital pin 13

int signal;               // Variable to store the pulse signal
int threshold = 550;      // Threshold for detecting a heartbeat
int heartRate;            // Variable to store heart rate
long lastBeat = 0;        // Time of the last beat
long beatInterval = 0;    // Interval between beats

void setup() {
  Serial.begin(9600);     // Initialize serial communication
  pinMode(ledPin, OUTPUT); // Set the LED pin as output
}

void loop() {
  signal = analogRead(pulsePin); // Read the pulse signal

  // If the signal is above the threshold, it's a beat
  if (signal > threshold) {
    if (millis() - lastBeat > 200) { // Debounce the beat
      heartRate = 60000 / (millis() - lastBeat); // Calculate heart rate
      lastBeat = millis(); // Update the last beat time
      digitalWrite(ledPin, HIGH); // Turn on the LED (optional)
    }
  } else {
    digitalWrite(ledPin, LOW); // Turn off the LED (optional)
  }

  // Print heart rate to the Serial Monitor
  if (heartRate > 0) {
    Serial.print("Heart Rate: ");
    Serial.print(heartRate);
    Serial.println(" BPM");
  }

  delay(100); // Short delay for stability
}

Code Explanation

  • Variables:
    • pulsePin: The analog pin where the pulse sensor is connected.
    • signal: Variable to store the reading from the pulse sensor.
    • threshold: Set the threshold value to detect heartbeats.
    • heartRate: Variable to store the calculated heart rate.
  • Setup Function:
    • Initializes serial communication and sets the LED pin as output.
  • Loop Function:
    • Reads the pulse signal from the sensor.
    • Checks if the signal exceeds the threshold to detect a heartbeat.
    • Calculates the heart rate based on the time interval between beats.
    • Prints the heart rate to the Serial Monitor.

Testing Your Heart Rate Monitor

1. Upload the code to your Arduino.

2. Open the Serial Monitor (Ctrl + Shift + M) in the Arduino IDE.

3. Place the pulse sensor on your fingertip or earlobe.

4. Observe the heart rate displayed in the Serial Monitor.

Conclusion

You have successfully built a simple heart rate monitor using Arduino. This project is a great introduction to working with sensors and can be expanded upon in various ways, such as adding an LCD to display the heart rate or logging data over time.

References

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