Pulse Sensor Using Arduino – Complete Guide with Simulation

Arduino Pulse Sensor
Heart Rate Monitor (BPM)

Measure and display real-time heart rate in Beats Per Minute (BPM) using a PPG-based Pulse Sensor and 16×2 I²C LCD — with simulation support so you can build it hardware-free.

🗓 Updated: April 2026 ⏱ Build time: ~30 min ⚡ Difficulty: Beginner ❤️ Biomedical / Health

⚕️ Educational Use Only This project is for learning and prototyping purposes only. It must not be used for clinical or professional medical diagnosis.

1 Project Overview

This beginner-friendly biomedical project measures heart rate in real time using the photoplethysmography (PPG) principle. The Pulse Sensor reads analog voltage changes caused by blood flow, sends the data to an Arduino UNO which calculates BPM, then displays the result on a 16×2 I²C LCD and Serial Monitor simultaneously.

The project is fully simulation-compatible — no physical hardware needed to learn the concept.

🫀

PPG-Based DetectionLED + photodetector measures blood-flow-induced light changes

📟

Dual OutputBPM shown on 16×2 LCD and Serial Monitor

🔗

I²C CommunicationSingle SDA/SCL bus for LCD

💻

Simulation ReadyTest on CircuitDesign.app without hardware

📚

Library-BasedUses PulseSensorPlayground for clean signal processing

🎚️

Adjustable ThresholdTune detection sensitivity for your environment

2 Components Required

🔵

Arduino UNO

× 1

❤️

Pulse Sensor (PPG)

× 1

🖥️

16×2 I²C LCD

× 1

I²C addr: 0x27

🔌

USB Cable

× 1 (Type-B)

🟡

Jumper Wires

× 8–10

⬜

Breadboard

× 1 (optional)

Required Libraries

Library	Purpose	Install via
PulseSensorPlayground	Pulse signal processing & BPM calculation	Arduino Library Manager
LiquidCrystal_I2C	16×2 I²C LCD control	Arduino Library Manager
Wire.h	I²C communication	Built-in (no install needed)

3 How Photoplethysmography (PPG) Works

The Pulse Sensor uses photoplethysmography — a non-invasive optical technique that detects blood volume changes in the microvascular tissue. Here's the 5-step process:

💡LED emits light into skin

→

🩸Blood flow absorbs varying light

→

👁️Photodetector measures intensity

→

⚡Analog voltage pulse output

→

📊Arduino calculates BPM from peaks

Each detected voltage peak = one heartbeat. The time between consecutive peaks is used to calculate the beats per minute value.

4 Circuit & Wiring Diagram

Fig 1 — Full wiring diagram. Pulse Sensor → A0 | LCD via I²C (A4=SDA, A5=SCL)

Pin Connection Reference

Device	Device Pin	Arduino Pin	Wire Colour
Pulse Sensor	VCC	5V	🟢 Green
Pulse Sensor	GND	GND	⚫ Black
Pulse Sensor	Signal	A0 (Analog)	🔵 Blue
16×2 I²C LCD	VCC	5V	🟢 Green
16×2 I²C LCD	GND	GND	⚫ Black
16×2 I²C LCD	SDA	A4 (SDA)	🟣 Purple
16×2 I²C LCD	SCL	A5 (SCL)	🟡 Yellow

6 Step-by-Step Instructions

Install Required Libraries

Open Arduino IDE → Sketch → Include Library → Manage Libraries. Search and install PulseSensorPlayground by Joel Murphy & Yury Gitman. Then install LiquidCrystal_I2C by Frank de Brabander. Wire.h is built-in.

In newer Arduino IDE 2.x, use the library panel on the left sidebar for faster searching.

Wire the Pulse Sensor to Arduino

Connect the three Pulse Sensor wires: VCC → 5V, GND → GND, Signal → A0. The sensor has a small PCB with an LED and photodiode facing down — place the component side against your fingertip.

Verify: No heat, no smoke. LED on the Pulse Sensor should faintly glow red when powered.

Wire the 16×2 I²C LCD

Connect the four LCD pins: VCC → 5V, GND → GND, SDA → A4, SCL → A5. The I²C backpack reduces the 16-pin LCD down to just 4 wires.

If your LCD shows blocks but no text, use a small screwdriver to adjust the blue contrast potentiometer on the I²C backpack.

Find Your LCD I²C Address

Most 16×2 I²C LCDs use address 0x27. If nothing displays, upload an I²C scanner sketch to find the correct address. Update this line in the code if needed:

LiquidCrystal_I2C lcd(0x27, 16, 2); // Change 0x27 if needed

Upload the Code

Open Arduino IDE, paste the full code from Section 7, select Board: Arduino UNO and the correct COM port, then click Upload. Wait for "Done uploading".

Open Serial Monitor at 9600 baud. You should see "Pulse sensor started successfully."

Place Your Finger on the Sensor

Rest your fingertip gently over the Pulse Sensor (LED side facing your skin). Keep steady pressure — not too hard. After 5–10 seconds, BPM values will appear on the LCD and Serial Monitor.

If readings are unstable, adjust the threshold value. Try values between 512 and 600 — lower = more sensitive.

Tune the Detection Threshold

The default threshold is 535. If you get false detections (very high BPM) increase it. If BPM isn't detected, decrease it. This value depends on your sensor, ambient light and skin tone.

pulseSensor.setThreshold(535); // Tune: 512–600 typical range

Test on Simulation (Optional)

Use the diagram.json from Section 5 to load the circuit in Wokwi or CirkitDesigner. The simulation generates synthetic pulse waveforms so you can verify the LCD output and code logic without any hardware.

Simulation BPM will be a fixed synthetic value — real hardware gives real readings.

7 Full Arduino Code

pulse_sensor_bpm.ino

/*
 * Arduino Sketch for Heart Pulse Sensor with LCD Display
 * MakeMindz.com — Arduino Pulse Sensor BPM Monitor
 *
 * Hardware:
 *   - Arduino UNO
 *   - Pulse Sensor (Signal → A0)
 *   - 16x2 I2C LCD (SDA→A4, SCL→A5, addr 0x27)
 *
 * Libraries:
 *   - PulseSensorPlayground
 *   - LiquidCrystal_I2C
 */

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <PulseSensorPlayground.h>

// Pin where the pulse sensor signal wire is connected
const int PULSE_SENSOR_PIN = A0;

// Create instance of PulseSensorPlayground
PulseSensorPlayground pulseSensor;

// Initialize LCD: I2C address 0x27, 16 columns, 2 rows
LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  // Start serial communication
  Serial.begin(9600);

  // Initialize LCD
  lcd.begin(16, 2);
  lcd.backlight();

  // Configure pulse sensor
  pulseSensor.analogInput(PULSE_SENSOR_PIN);
  pulseSensor.setSerial(Serial);
  pulseSensor.setThreshold(535);  // Adjust for sensitivity (512–600)

  // Attempt to start the pulse sensor
  if (pulseSensor.begin()) {
    Serial.println("Pulse sensor started successfully.");
    lcd.setCursor(0, 0);
    lcd.print("Pulse Sensor OK");
  } else {
    Serial.println("Pulse sensor failed to start.");
    lcd.setCursor(0, 0);
    lcd.print("Sensor Fail");
  }
}

void loop() {
  // Get current BPM from library
  int myBPM = pulseSensor.getBeatsPerMinute();

  // If a new heartbeat peak was detected
  if (pulseSensor.sawStartOfBeat()) {
    Serial.print("BPM: ");
    Serial.println(myBPM);

    // Update LCD row 1 (row 0 = status line)
    lcd.setCursor(0, 1);
    lcd.print("BPM: ");
    lcd.print(myBPM);
    lcd.print("    ");  // Clear trailing digits
  }

  // Small delay for stable readings
  delay(10);
}

8 Key Library Functions Explained

pulseSensor.analogInput(A0)

Tells the library which Arduino pin is connected to the sensor's signal wire. Must be called before begin().

pulseSensor.setThreshold(535)

Sets the minimum signal strength to count as a heartbeat. Lower = more sensitive. Default 535 works for most setups. Range: 0–1023.

pulseSensor.begin()

Initialises the sensor and starts background sampling using a hardware timer interrupt. Returns true if successful.

pulseSensor.sawStartOfBeat()

Returns true once per detected heartbeat peak. Use this to trigger your BPM display update — it fires only on a new beat.

pulseSensor.getBeatsPerMinute()

Returns the calculated BPM as an integer, based on the time interval between the last two detected peaks.

pulseSensor.setSerial(Serial)

Enables the built-in serial output for debugging. Waveform data is streamed to Serial Monitor at the configured baud rate.

9 Simulation Links

Test this project entirely online — no hardware required. These platforms let you simulate the Arduino, Pulse Sensor and LCD all in your browser.

🟢

Wokwi Simulator

Paste the diagram.json and code directly. Supports PulseSensorPlayground library. Full LCD simulation included.

▶ Open Wokwi →

🔵

CirkitDesigner

Drag-and-drop circuit builder with Arduino UNO, Pulse Sensor and LCD components. Great for STEM students.

▶ Open CirkitDesigner →

🟡

Tinkercad Circuits

Beginner-friendly Arduino simulator by Autodesk. Use with a custom analog signal source for pulse testing.

▶ Open Tinkercad →

📋 Simulation Instructions 1. Go to Wokwi.com and create a new Arduino UNO project. 2. Click the diagram.json tab and paste the JSON from Section 5. 3. Click sketch.ino and paste the full code from Section 7. 4. Press the ▶ Play button to start simulation and watch BPM appear on the LCD.

10 Key Features

❤️

Real-Time BPMContinuous heart rate measurement using PPG

📟

Dual DisplayLCD shows BPM; Serial Monitor shows waveform data

📚

Library-BasedClean code using PulseSensorPlayground library

🎚️

Tunable ThresholdAdjustable sensitivity for different conditions

💻

Simulation-ReadyWorks in Wokwi and CirkitDesigner

🔗

Minimal WiringOnly 7 connections total for full system

🎓

Beginner FriendlyClear code, simple circuit, full tutorial

🏥

STEM / BiomedicalIdeal for science fairs and IoT health projects

11 Possible Upgrades

📡ESP32 Wi-Fi version — send BPM to cloud

📱Mobile app dashboard via Bluetooth

☁️Cloud logging: ThingSpeak or Firebase

📈OLED waveform graph display

🔋Battery-powered wearable design

🚨Abnormal BPM buzzer alert system

🌡️Add SpO₂ (blood oxygen) with MAX30102

📊BPM history logging to SD card

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