Heart-Rate-Monitoring-System-using-Pulse-Sensor-and-OLED-Display-main

Heart Rate Monitoring System

ESP32, Pulse Sensor & OLED Interface

Launch Interactive Circuit Space

👁️ Operational Overview System Logic

This biomedical monitoring project utilizes an ESP32 processing core to capture blood volume changes caused by arterial tissue contraction pulse waves. By scanning the analog telemetry stream outputted by a specialized Pulse Sensor module, a threshold-driven heartbeat detection algorithm measures precise time intervals between beats to extract stabilized real-time Beats Per Minute (BPM). Visual telemetry arrays are simultaneously routed down active serial pipes and onto a sleek 0.96-inch SSD1306 OLED interface monitor.

Heartbeat Mathematical Formula

📊 BPM = 60000 / Beat Interval (ms)

HCI Pulse Status Tracking

❤️ Visual Heart Indicator (<3) Toggle

📺 Project Demonstration & Guide Video Hub

Watch the full demonstration, calibration configuration walkthrough, and biotelemetry testing live below:

🛠... Structural BOM Requirements Hardware List

Procure the following components to execute the core prototyping phase layout configurations:

Target Component Label	Structural Allocation Quantity	Functional Deployment Purpose
ESP32 Development Board	1 Unit	Central processing execution core and telemetry clock loop.
Pulse Sensor Transducer Module	1 Unit	Real-time peripheral blood volume change sensory capture.
0.96" SSD1306 OLED Display (I2C)	1 Unit	High-contrast visual interface for real-time telemetry metrics tracking.
Prototyping Breadboard & Wires	1 Set	Solderless hardware interface routing connection matrix.

🔌 Device Interface Pin Maps I/O Infrastructure

Wire the physical subsystem communication buses in accordance with the following structured reference maps:

Pulse Sensor Block Wiring Matrix:

Sensor Transducer Node Pin	ESP32 Host Mapping Node Pin
VCC (Module Power)	3.3V Power Output Rail
GND (Ground Return Plane)	GND Common Reference Ground
Signal (Analog Data Output)	GPIO 13 Analog Intercept Node

0.96" SSD1306 OLED Display (I2C) Module Map:

Character Display I2C Board Node	ESP32 Master Mapping Pin Interface
VCC (Module Power)	3.3V Shared Positive Voltage Rail
GND (Module Ground)	GND Shared Reference Ground Plane
SDA (I2C Serial Data Line)	GPIO 21 Dedicated Communication Node
SCL (I2C Serial Clock Line)	GPIO 20 Dedicated Communication Node

💻 Optimized Production Code Engine Firmware Source

Copy and integrate this production-ready code directly into your local desktop Arduino IDE environment:

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
#define SCREEN_ADDRESS 0x3C

// Pins matching your circuit image
#define PULSE_PIN 13
#define SDA_PIN 21
#define SCL_PIN 20

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// BPM Tracking Variables
unsigned long lastBeatTime = 0;
unsigned long currentBeatTime = 0;

// Adjusted for 16-bit scale (0-65535). Midpoint is roughly 35000 at 3.3V
int threshold = 35000;               
bool anyBeat = false;
int bpm = 0;

void setup() 
{
    Serial.begin(115200);
    
    // REMOVED: pinMode(PULSE_PIN, INPUT) as it glitches ESP32 analog reads.

    // Initialize I2C with your exact pins: SDA=21, SCL=20
    Wire.begin(SDA_PIN, SCL_PIN);

    // Initialize OLED Display
    if(!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
        Serial.println(F("SSD1306 allocation failed"));
        for(;;);
    }
    
    display.setTextColor(SSD1306_WHITE);
    display.clearDisplay();
    display.display();
    
    Serial.println("Heart Rate Monitor Started");
}

void loop() 
{
    // Read the analog signal from the Pulse Sensor
    int signalValue = analogRead(PULSE_PIN);
    
    // Heartbeat detection logic
    if (signalValue > threshold && anyBeat == false) 
    {
        anyBeat = true;
        currentBeatTime = millis();
        
        unsigned long beatDuration = currentBeatTime - lastBeatTime;
        
        // Debounce: Human heart standard range
        if (beatDuration > 300 && beatDuration < 2000) 
        {
            bpm = 60000 / beatDuration; 
        }
        
        lastBeatTime = currentBeatTime;
    }

    // Reset the beat flag when the signal drops back below the threshold
    if (signalValue < (threshold - 2000)) 
    {
        anyBeat = false;
    }

    // Print to Serial Monitor
    Serial.print("Signal:");
    Serial.print(signalValue);
    Serial.print(",");
    Serial.print("BPM:");
    Serial.println(bpm);

    // Draw everything to the OLED Screen
    display.clearDisplay();
    
    display.setTextSize(1);
    display.setCursor(15, 0);
    display.println("HEART RATE MONITOR");
    
    display.drawFastHLine(0, 12, 128, SSD1306_WHITE);

    display.setCursor(0, 22);
    display.print("Signal: ");
    display.print(signalValue);

    display.setCursor(100, 22);
    if(anyBeat) {
        display.print("<3"); 
    } else {
        display.print("  ");
    }

    display.setTextSize(2);
    display.setCursor(0, 42);
    display.print("BPM: ");
    if (bpm > 30 && bpm < 200) {
        display.print(bpm);
    } else {
        display.print("---"); 
    }

    display.display();
    
    delay(20); 
}

HCI Stability Note: Human baseline tracking parameters are built-in. The firmware includes a software noise debounce threshold limit (300ms to 2000ms intervals) to discard aberrant noise artifacts from raw skin proximity shifts.