#include <DHT.h> // Using DHT Library
#include <U8g2lib.h> // Using U8g2 Library
#include <Wire.h>

#define DHTPIN 26     // DHT11 I/O pin connected
#define DHTTYPE DHT11   // Sensor type (DHT11, DHT21, DHT22)

DHT dht(DHTPIN, DHTTYPE); // define DHT Object named 'dht' with previous define pin and type

// OLED display constructor
U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE, /* clock=*/ 3, /* data=*/ 4);

void setup() {
  Serial.begin(9600); // start serial communication with baud rate
  dht.begin(); // start dht sensor read
  u8g2.begin(); // Initialize the OLED display
}

void loop() {
  delay(1000);  // wait 1 sec between each sensor read
  u8g2.clearBuffer(); // Clear the screen
  // Set font and position
  u8g2.setFont(u8g2_font_ncenB14_tr);
  u8g2.setCursor(0, 20); // Set position (x, y)
  // Reading DHT11 data
  float humidity = dht.readHumidity();    // Read humidity in %
  float temperature = dht.readTemperature();  // Read temperature in °C

  // Checking if reading data succeed
  if (isnan(humidity) || isnan(temperature)) { // if data read "is not a number"
    Serial.println("Failed to read DHT11 Sensor !"); //print on serial monitor error message
    u8g2.println("Failed to read DHT11 Sensor !");
    return;
  }

  // Displaying data on serial monitor :
  u8g2.print("Humidity: ");
  u8g2.print(humidity);
  u8g2.print(" %\t");
  u8g2.print("Temperature: ");
  u8g2.print(temperature);
  u8g2.println(" °C");
  u8g2.sendBuffer();
  // Displaying data on serial monitor :
  Serial.print("Humidity: ");
  Serial.print(humidity);
  Serial.print(" %\t");
  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.println(" °C");
}