/*

Voltaat learn (http://learn.voltaat.com)

Link for full tutorial:

Tutorial: Building a device to read and graph heart rate using Arduino and MAX30102!

The purpose of this sketch is to build a device to read and chart the heart rate using

an Arduino board and a heart rate sensor to capture vital signs. We will use a screen

to display the results visually and also display the results through a graph on the computer.

Connections from the Arduino to the breadboard:

• Arduino GND pin → Breadboard ground line

• Arduino 5V pin → Breadboard 5V line

Connection from the LCD:

• VCC pin → breadboard 5v line

• GND pin→ breadboard GND line

• SDA pin→ Arduino analog pin A4

• SCL pin → Arduino analog pin A5

Connections from the Heartbeat Sensor:

• VCC pin → breadboard 5v line

• GND pin→ breadboard GND line

• SDA pin→ Arduino analog pin A4

• SCL pin → Arduino analog pin A5

Connections from the buzzer:

• The positive terminal of the speaker → Pin 2 on the Arduino board

• The negative terminal of the speaker → Negative terminals on the breadboard

*/

#include "MAX30105.h"

#include "heartRate.h"

#include "LiquidCrystal_I2C.h"

// Initialize MAX30105 pulse sensor

MAX30105 particleSensor;

// Initialize LCD display with I2C address 0x27, 16 columns, and 2 rows

LiquidCrystal_I2C lcd(0x27, 16, 2);

// Define heart shape character for LCD

byte heartChar[8] = {

0b00000,

0b01010,

0b11111,

0b11111,

0b01110,

0b00100,

0b00000,

0b00000

};

const byte RATE_SIZE = 7; // Number of readings to calculate the average BPM

byte rates[RATE_SIZE]; // Array to store heart rate values

byte rateSpot = 0; // Index for storing heart rate readings

long lastBeat = 0; // Timestamp of the last detected heartbeat

float beatsPerMinute; // Instant BPM value

int beatAvg; // Average BPM value

unsigned long previousMillis = 0;

const long interval = 1000; // LCD update interval (1 second)

int buzzer = 3; // Buzzer pin

void setup() {

Serial.begin(9600); // Initialize serial communication

pinMode(buzzer, OUTPUT); // Set buzzer pin as output

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

lcd.backlight(); // Turn on LCD backlight

lcd.createChar(0, heartChar); // Register the custom heart character

lcd.print("Initializing...");

// Check if the MAX30105 sensor is detected

if (!particleSensor.begin(Wire, I2C_SPEED_FAST)) {

  lcd.clear();

  lcd.print("Sensor Error!");

  while (1); // Halt execution if sensor is not found

}

particleSensor.setup(); // Configure the sensor

particleSensor.setPulseAmplitudeRed(0x0A); // Set LED pulse amplitude for red light

}

void loop() {

long irValue = particleSensor.getIR(); // Read IR sensor value

// Check if a heartbeat is detected

if (checkForBeat(irValue)) {

  long delta = millis() - lastBeat; // Calculate time between beats

  lastBeat = millis(); // Update last beat timestamp

 

  beatsPerMinute = 60 / (delta / 1000.0); // Convert time difference to BPM

  // Validate BPM range to filter out noise

  if (beatsPerMinute > 20 && beatsPerMinute < 255) {

    rates[rateSpot++] = (byte)beatsPerMinute; // Store BPM in the array

    rateSpot %= RATE_SIZE; // Loop back index when it reaches max size

    // Calculate the average BPM

    beatAvg = 0;

    for (byte x = 0; x < RATE_SIZE; x++) beatAvg += rates[x];

    beatAvg /= RATE_SIZE;

   

  }

}

// Update the LCD every second

if (millis() - previousMillis >= interval) {

  previousMillis = millis();

  lcd.clear();

  // Display BPM on the first row

  lcd.setCursor(0, 0);

  lcd.print("BPM: ");

  lcd.print(beatAvg);

  Serial.println(beatAvg); // Print BPM to serial monitor

 

  // Show heart symbol if a recent beat is detected

  if (millis() - lastBeat < 1000) {

    lcd.setCursor(13,0);

    lcd.write(0); // Display heart symbol

  }

  // Display BPM status on the second row

  lcd.setCursor(1,1);

  if (beatAvg < 60) {

    lcd.print("LOW BPM");

  }

  else if (beatAvg > 100){

    lcd.print("High BPM");

    digitalWrite(buzzer, HIGH); // Activate buzzer for high BPM

  }

  else {

    lcd.print("Normal BPM");

    digitalWrite(buzzer, LOW); // Turn off buzzer

  }

  // Show heart symbol again if a recent beat is detected

  if (millis() - lastBeat < 1000) {

    lcd.setCursor(13,0);

    lcd.write(0); // Display heart symbol

  }

  // If IR value is too low, prompt user to place a finger

  if (irValue < 50000) {

    lcd.clear();

    lcd.print("Place finger?");

  }

}

}

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