/*
Smart Temperature Alarm System (2-LED Version)
Bachelor Project - Informatik
Author: [Your Name] 
Date: March 2026

Hardware: DHT22 + LCD + Buzzer + 2 LEDs (Green/Red)

*/

#include <DHT.h>
#include <LiquidCrystal.h>

// Pin definitions (EXACTLY your wiring)
#define DHT_PIN 2         // DHT22 → Arduino Pin 2
#define DHT_TYPE DHT22
#define BUZZER_PIN 8      // Buzzer pin
#define LED_GREEN 4       // Green LED (Normal temp)
#define LED_RED 5         // Red LED (Hot temp)

// Temperature thresholds (°C)
const float TEMP_NORMAL_HIGH = 28.0;  // Above = HOT
const float TEMP_ALARM = 30.0;        // Buzzer alarm

// Initialize components
DHT dht(DHT_PIN, DHT_TYPE);
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
  Serial.begin(9600);
  Serial.println("=== Smart Temperature Alarm (2-LED) ===");
  
  // Configure pins
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(LED_GREEN, OUTPUT);
  pinMode(LED_RED, OUTPUT);
  
  // Initialize DHT22
  dht.begin();
  
  // Initialize LCD
  lcd.begin(16, 2);
  lcd.setCursor(0, 0);
  lcd.print("Temp Alarm 2-LED");
  lcd.setCursor(0, 1);
  lcd.print("Initializing...");
  delay(2000);
  lcd.clear();
}

void loop() {
  // Read sensors
  float temp = dht.readTemperature();
  float hum = dht.readHumidity();
  
  // Error handling
  if (isnan(temp) || isnan(hum)) {
    Serial.println("ERROR: DHT22 reading failed");
    lcd.clear();
    lcd.print("SENSOR ERROR!");
    delay(2000);
    return;
  }
  
  // Serial output (for professor demo)
  Serial.print("T: "); Serial.print(temp, 1);
  Serial.print("°C  H: "); Serial.print(hum, 1); Serial.println("%");
  
  // Update display and LEDs
  updateDisplay(temp, hum);
  updateLEDs(temp);
  checkAlarm(temp);
  
  delay(2000);  // DHT22 sampling interval
}

/**
 * LCD Display Update
 */
void updateDisplay(float temp, float hum) {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Temp: "); lcd.print(temp, 1); lcd.print(" C");
  
  lcd.setCursor(0, 1);
  lcd.print("Humidity: "); lcd.print(hum, 1); lcd.print("%");
}

/**
 * 2-LED Status Control
 */
void updateLEDs(float temp) {
  digitalWrite(LED_GREEN, LOW);
  digitalWrite(LED_RED, LOW);
  
  if (temp <= TEMP_NORMAL_HIGH) {
    digitalWrite(LED_GREEN, HIGH);  // Normal temperature
  } else {
    digitalWrite(LED_RED, HIGH);    // Hot temperature
  }
}

/**
 * Buzzer Alarm (>30°C)
 */
void checkAlarm(float temp) {
  if (temp >= TEMP_ALARM) {
    digitalWrite(BUZZER_PIN, HIGH);
    Serial.println("*** ALARM: Critical Temperature! ***");
    delay(500);
    digitalWrite(BUZZER_PIN, LOW);
    delay(1000);
  } else {
    digitalWrite(BUZZER_PIN, LOW);
  }
}