#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
#define OLED_RESET     -1 // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);


//RTC
#include <RTClib.h>
RTC_DS3231 rtc;
DateTime nows;

void setup() {
  Serial.begin(115200);

  // SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    while(1); //for (;;); // Don't proceed, loop forever
  }

  // Clear the buffer
  //atur ukuran tulisan
  display.setTextSize(1);      // ukuran normal 1:1
  display.setTextColor(WHITE); // tulisan warna putih
  display.clearDisplay();
  display.print("test RTC");
  display.display();
  delay(1000);


  Serial.println(F("\r\nCek RTC"));
  display.setCursor(0, 20);
  display.print("CEK RTC");
  display.display();
  delay(1000);

  if (!rtc.begin()) {
    Serial.println(F("RTC Error"));
    display.setCursor(0, 30);
    display.print("RTC  ERROR!!!");
    display.display();
    while (1);
  }
  else {
    Serial.println(F("\r\nRTC OK"));
    display.setCursor(0, 30);
    display.print("RTC OK!");
    display.display();
  }

  delay(1000);

  display.clearDisplay();
}

void loop() {
    display.clearDisplay();
  nows = rtc.now();
  int tahun = nows.year();
  byte bulan = nows.month();
  byte hari = nows.day();
  byte jam = nows.hour();
  byte menit = nows.minute();
  byte detik = nows.second();

  char tanggal[20]="yyyy/mm/dd hh:mm:ss";

  sprintf(tanggal,"%d/%d/%d %02d:%02d:%02d", tahun, bulan, hari, jam, menit, detik);
Serial.println(tanggal);
  display.setCursor(0,0);
  display.print(tanggal);
  display.display();
  delay(1000);
}