#include <LiquidCrystal_I2C.h>
#include <DHT.h>

// LCD settings
LiquidCrystal_I2C lcd(0x27, 16, 2);  // LCD address and dimensions

// DHT sensor settings (upgrade to DHT22 for wider range)
#define DHTPIN 11    // Pin where the DHT is connected
#define DHTTYPE DHT22 // Use DHT22 for real-life weather station, supports negative values
DHT dht(DHTPIN, DHTTYPE);

// Custom degree symbol
byte degree_symbol[8] = {
  0b00111,
  0b00101,
  0b00111,
  0b00000,
  0b00000,
  0b00000,
  0b00000,
  0b00000
};

// Calibration offsets (adjust these if you have calibration data)
float tempCalibrationOffset = 0.0;  // Temperature offset (for sensor calibration)
float humCalibrationOffset = 0.0;   // Humidity offset

void setup() 
{
  lcd.init();                     // Initialize the LCD
  lcd.backlight();
  lcd.print("Temp = ");
  lcd.setCursor(0, 1);
  lcd.print("Humidity = ");
  
  lcd.createChar(1, degree_symbol);  // Create degree symbol
  lcd.setCursor(9, 0);
  lcd.write(1);                      // Display degree symbol
  lcd.print("C");
  lcd.setCursor(13, 1);
  lcd.print("%");

  dht.begin(); // Initialize the DHT sensor
}

void loop() 
{
  // DHT11 needs a 2-second interval between readings
  delay(2000);

  const int numReadings = 5;  // Number of readings to average
  float tempSum = 0;
  float humSum = 0;
  int validReadings = 0;

  // Take multiple readings for better accuracy
  for (int i = 0; i < numReadings; i++) {
    float temperature = dht.readTemperature();
    float humidity = dht.readHumidity();

    // Check if readings are valid
    if (!isnan(temperature) && !isnan(humidity)) {
      tempSum += temperature;
      humSum += humidity;
      validReadings++;
    }
    delay(1000); // Wait 1 second between readings
  }

  if (validReadings > 0) {
    // Calculate average and apply calibration offsets
    float avgTemp = (tempSum / validReadings) + tempCalibrationOffset;
    float avgHum = (humSum / validReadings) + humCalibrationOffset;

    // Ensure values are within sensor's range
    avgTemp = constrain(avgTemp, -40.0, 80.0);  // Adjust as needed for your sensor
    avgHum = constrain(avgHum, 0.0, 100.0);

    // Clear previous temperature value
    lcd.setCursor(7, 0);
    lcd.print("    ");  // Clear four characters
    lcd.setCursor(7, 0);
    lcd.print(avgTemp, 1);  // Display temperature with 1 decimal, supports negative values

    // Clear previous humidity value
    lcd.setCursor(11, 1);
    lcd.print("    ");  // Clear four characters
    lcd.setCursor(11, 1);
    lcd.print(avgHum, 1);   // Display humidity with 1 decimal
  } else {
    // Display error if readings are invalid
    lcd.setCursor(7, 0);
    lcd.print("Err ");
    lcd.setCursor(11, 1);
    lcd.print("Err ");
  }
}