#include <DHT.h>

#define DHT22_PIN 13 // ESP32 pin GPIO23 connected to DHT22
#define RELAY_PIN 18 // ESP32 pin GPIO18 connected to relay

#define DHT_SENSOR_TYPE DHT22

#define TEMP_THRESHOLD  30 // upper temperature threshold
//#define TEMP_LOWER_THRESHOLD  15 // lower temperature threshold

DHT dht22(DHT22_PIN, DHT_SENSOR_TYPE);

void setup() {
  Serial.begin(9600); // initialize serial
  dht22.begin(); // initialize the DHT sensor
  pinMode(RELAY_PIN, OUTPUT);
}

void loop() {
  float temperature = dht22.readTemperature();;  // read temperature in Celsius

  if (isnan(temperature)) {
    Serial.println("Failed to read from DHT22 sensor!");
  } else {
    if (temperature > TEMP_THRESHOLD) {
      Serial.println("Turn the relay on");
      digitalWrite(RELAY_PIN, HIGH); // turn on
    } else {
      Serial.println("Turn the relay off");
      digitalWrite(RELAY_PIN, LOW); // turn off
    }
  }

  // wait a 1 seconds between readings
  delay(1000);
}