#include <Wire.h>   //Calling of library for I2C interface.
#include <LiquidCrystal_I2C.h> //Calling of library for LCD display function with I2C.
#include <Adafruit_SSD1306.h>  //Calling of library for OLED display function.
#include <Adafruit_GFX.h>  //Calling of library for OLED display function.
#include <RTClib.h>  //Calling of library for RTC module,s function

RTC_DS1307 Time;  // An object creation for ds1307 RTC module. 

LiquidCrystal_I2C lcd(0x27,16,2);  // Set the LCD address to 0x27 for a 16 chars and 2 line display
Adafruit_SSD1306 display(128,64);  // Set dimention of OLED display (128*64).

void setup() {   // Set up function initialization. 
  lcd.init();  // Initialization of LCD display.
  lcd.backlight();   // Command for flashing bak light of LCD.

  display.begin(SSD1306_SWITCHCAPVCC, 0x3C); // Initialization of OLED display with 0x3C address.

  Time.begin();  //Initialization of ds1307 module for real time.
}   // Set up function closing.

void loop() {  // Loop function initialization.
  DateTime Real = Time.now();  // Object creation and calling a function of calculating the real time. 
  lcd.setCursor(0,0);   // Selection of Starting position of LCD display.
  lcd.print("Time = ");  // Printing of text "Time" in LCD display.
  lcd.print(Real.hour());  // Printing of hour in LCD display.
  lcd.print(":");
  lcd.print(Real.minute());  // Printing of minute in LCD display.
  lcd.print(":");
  lcd.print(Real.second());  // Printing of second in LCD display.
  lcd.print(".");

  display.clearDisplay();  // A command for clearing default text or picture in OLED display.
  display.setCursor(15,0);  // Selection of Starting position of OLED display.
  display.setTextSize(3);  // Selection of font size of text in OLED display.
  display.setTextColor(SSD1306_WHITE);  // Selection of color size of text in OLED display.
  display.print("-Time-");  // Printing of text "Time" in OLED display.
  display.setCursor(25,40);  // Selection of Starting position for another text of OLED display.
  display.setTextSize(2);  // Selection of font size of another text in OLED display.
  display.setTextColor(SSD1306_WHITE); // Selection of color size of another text in OLED display.
  display.print(Real.hour());  // Printing of hour in OLED display.
  display.print(":");
  display.print(Real.minute());  // Printing of minute in OLED display.
  display.print(":");
  display.print(Real.second());  // Printing of second in OLED display.
  display.print(".");
  display.display();  // A command for displaying in OLED display.
}  // Loop function closing.