#include <DHT.h>
#define DHTPIN 13
#define DHTTYPE DHT22

DHT dht(DHTPIN, DHTTYPE);

const int relayPin = 4;
float hum;
float temp;

void setup() {
  pinMode(relayPin, OUTPUT);
  digitalWrite(relayPin, LOW);
  Serial.begin(115200);
  dht.begin();
  
  delay(2000);
  Serial.println(F("DHT22 Temperature & Humidity Control"));
}

void loop() {
  hum = dht.readHumidity();
  temp = dht.readTemperature();

  if (isnan(hum) || isnan(temp)) {
    Serial.println(F("Failed to read from DHT sensor!"));
    digitalWrite(relayPin, LOW); 
    delay(2000);
    return;
  }

  Serial.print(F("Humidity: "));
  Serial.print(hum);
  Serial.print(F("%  Temperature: "));
  Serial.print(temp);
  Serial.println(F("°C"));

  if (temp >= 20 && temp <= 30) {
    Serial.println(F("Temperature in range (20-30°C) - Relay ON for 5 seconds"));
    digitalWrite(relayPin, HIGH);
    delay(5000);
    digitalWrite(relayPin, LOW);
    Serial.println(F("Relay OFF"));
  } else {
    Serial.println(F("Temperature out of range - Relay remains OFF"));
    digitalWrite(relayPin, LOW);
  }
  
  delay(1000);
}