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

// Initialize the LCD with the I2C address 0x27
LiquidCrystal_I2C lcd(0x27, 16, 2);

const int heartRatePin = A0;
const int tempPin = A1;
const int bpPin = A2;

// Buzzer and LED pins
const int buzzerPin = 8; 
const int ledPin = 9;    

// NTC Thermistor configuration
const float BETA = 3950; // Beta coefficient of the thermistor

// Thresholds for alerts
const float TEMP_THRESHOLD = 30.0; 
const int HEART_RATE_THRESHOLD = 95; 

void setup() {
  // Initialize the LCD
  lcd.begin(16, 2);
  lcd.print("Health Monitor");

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

  // Set up the pins
  pinMode(heartRatePin, INPUT);
  pinMode(tempPin, INPUT);
  pinMode(bpPin, INPUT);
  pinMode(buzzerPin, OUTPUT);
  pinMode(ledPin, OUTPUT);
}

void loop() {
  // Read values from the sensors
  int heartRateValue = analogRead(heartRatePin);
  int tempValue = analogRead(tempPin);
  int bpValue = analogRead(bpPin);

  // Convert heart rate sensor reading to meaningful value
  int heartRate = map(heartRateValue, 0, 1023, 60, 100); 
  
  // Calculate temperature from the NTC thermistor
  float celsius = 1 / (log(1 / (1023.0 / tempValue - 1)) / BETA + 1.0 / 298.15) - 273.15;

  // Convert blood pressure sensor reading to meaningful value
  int bloodPressure = map(bpValue, 0, 1023, 80, 120);

  // Check if the readings exceed thresholds and activate alerts
  bool alert = false;
  
  if (celsius > TEMP_THRESHOLD || heartRate > HEART_RATE_THRESHOLD) {
    alert = true;
  }

  if (alert) {
    tone(8, 262, 250);
    digitalWrite(buzzerPin, HIGH); 
    digitalWrite(ledPin, HIGH);    
  } else {
    digitalWrite(buzzerPin, LOW); 
    digitalWrite(ledPin, LOW);     
  }

  // Print values to serial monitor
  Serial.print("Heart Rate: ");
  Serial.print(heartRate);
  Serial.print(" BPM, Temperature: ");
  Serial.print(celsius);
  Serial.print(" C, Blood Pressure: ");
  Serial.print(bloodPressure);
  Serial.println(" mmHg");

  // Display values on the LCD
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("HR:");
  lcd.print(heartRate);
  lcd.print(" BPM");

  lcd.setCursor(0, 1);
  lcd.print("Temp:");
  lcd.print(celsius);
  lcd.print("C BP:");
  lcd.print(bloodPressure);
  lcd.print("mmHg");

  delay(1000); // Update every second
}