Simple Heartbeat Monitor Circuit using Arduino

In this post we will show how to make Simple Heartbeat Monitor Circuit using Arduino.

When we put finger on sensor it count heartbeats per minute.

This is important because heartbeat tells doctor about our health.

We use Arduino UNO, LCD screen, two buttons, one resistor and heartbeat sensor to build it.

Sensor catches heartbeat signal and Arduino read it and show heartbeat on screen.

Two buttons control screen and heartbeat check.

Coding:

#include <LiquidCrystal.h>

// Define pins for components
const int heartRatePin = A0;
const int startButtonPin = 2;
const int stopButtonPin = 3;
const int lcdContrastPin = 4;

// Create LCD object
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
  // Set pins as input or output
  pinMode(heartRatePin, INPUT);
  pinMode(startButtonPin, INPUT_PULLUP);
  pinMode(stopButtonPin, INPUT_PULLUP);
  pinMode(lcdContrastPin, OUTPUT);

  // Initialize LCD display
  lcd.begin(16, 2);
  lcd.setCursor(0, 0);
  lcd.print("Heartbeat Monitor");
}

void loop() {
  // Read heart rate sensor value
  int sensorValue = analogRead(heartRatePin);

  // Calculate heart rate (adjust factors as needed)
  int heartRate = (sensorValue * 60) / 1023;

  // Display heart rate on LCD
  lcd.setCursor(0, 1);
  lcd.print("HR: ");
  lcd.print(heartRate);
  lcd.print(" BPM");

  // Check for button presses
  if (digitalRead(startButtonPin) == LOW) {
    // Start heart rate measurement
    // ... (your code here)
  }

  if (digitalRead(stopButtonPin) == LOW) {
    // Stop heart rate measurement
    // ... (your code here)
  }
}

Code Explanation:

• Arduino read heart rate sensor value from A0 pin (analog read).
• Heart give tiny electric signals and this make value go up and down.
• To make reading better, code uses filter or average to remove noise.
• Analog value from 0 to 1023 is changed to BPM (beats per minute).
• Sensor setting and how sensitive it is decide how value change to BPM.
• Formula like (sensorValue * 60) / 1023 is used but may change based on sensor.
• LCD show “HR:” and number with “BPM” after it.
• Start and stop buttons use pull-up resistor.
• Button normally high (1) go low (0) when pressed.
• Code checks the button press and start button begin heartbeat check and this stops the button and pauses it.

Circuit Working:

Parts List:

Component	Quantity
Resistors
100k 1/4 watt	2
Potentiometer 10k	1
Semiconductors
Arduino UNO	1
Heart Beat sensor module	1
16×2 LCD	1
Push button tactile switches	2
IC 7809	1

Arduino UNO get steady 9V power using 7809 voltage regulator.

This is good because Arduino need 5V to work.

Heartbeat is found using heartbeat sensor module.

Sensor uses infrared to see blood flow change when heart pump.

These changes become small electric signal (pulse).

Sensor send analog signal to Arduino UNO.

Arduino read this signal, calculate heart rate and show it on LCD.

Press start button pin 2 to begin.

It turn on sensor, clear old data and set LCD for display.

Press stop button to pause or stop.

It turns OFF sensor, save data and show stop message on screen.

Potentiometer is used to change LCD contrast.

How to Build:

To build a Simple Heartbeat Monitor Circuit using Arduino following are the steps to follow:

• First collect all parts same like in circuit diagram.
• Connect 7809 IC to give steady 9V DC to Arduino.
• Connect 10k pot 1st pin to LCD VCC
• 2nd pin of 10k pot goes to LCD contrast pin
• 3rd pin of 10k pot goes to LCD GND.
• One leg of start button goes to Arduino pin 2
• Other leg of start button goes to GND.
• One leg of stop button goes to Arduino pin 3
• Other leg of stop button goes to GND.
• Put 100k resistor between pin 2 and 5V on Arduino.
• Put other 100k resistor between pin 3 and 5V on Arduino.
• 1st pin of heartbeat sensor goes to 5V on Arduino
• 2nd pin of heartbeat sensor goes to GND
• 3rd pin of heartbeat sensor goes to A0 on Arduino.
• Connect LCD R/W pin to GND on Arduino.
• Connect LCD backlight cathode to GND.
• Connect LCD backlight anode to 5V on Arduino.

Below table shows connections of an LCD Display to Arduino board:

Arduino Pin	LCD Pin	Description
5V	VCC	Power supply
GND	GND	Ground
D2	RS	Register select
D3	E	Enable
D4, D5, D6, D7	D4, D5, D6, D7	Data pins

Conclusion:

This project for Simple Heartbeat Monitor Circuit using Arduino show simple heartbeat monitor.

Code give basic way to find and show heart rate.

It also tell how to connect parts and make circuit.

We can make it better by adding features like to save heart rate data, show average heart rate and give light or screen alerts.

References:

Heart Rate Monitor Project