#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <Wire.h>
#ifdef ARDUINO_ARCH_MEGAAVR
#include "EveryTimerB.h"
#define Timer1 TimerB2 // use TimerB2 as a drop in replacement for Timer1
#else // assume architecture supported by TimerOne ....
#include "TimerOne.h"
#endif

#define MICROSEKUNDEN 680000
#define UP_PIN 2
#define DOWN_PIN 3

enum MODE{ RUN, SET_HOUR, SET_MIN, SET_SEC };
enum MODE mode = RUN;

volatile bool blink = false;
volatile long hour = 0;
volatile long minute = 0;
volatile long second = 0;
volatile long count_sec = 72000;

#define OLED_RESET 4
Adafruit_SSD1306 display(OLED_RESET);

void Timer1_Interrupt() 
{
  ++count_sec %= 86400;
}


void setup() {
  Timer1.initialize(MICROSEKUNDEN);
  Timer1.attachInterrupt(Timer1_Interrupt);
  Serial.begin( 9600 );
  pinMode( UP_PIN,   INPUT_PULLUP );
  pinMode( DOWN_PIN, INPUT_PULLUP );
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  display.clearDisplay();
  display.setTextSize(2);
  display.setTextColor(WHITE);
  //display.setCursor(0,0);
  //display.print("Uhrzeit: ");
  //display.display();
}

void loop() {
  display.clearDisplay();
  display.setCursor( 30, 10 );
  display.print(  count_sec );
  display.display();
  delay( 10 );
}

/*
#include "TimerOne.h"  
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

#define MICROSEKUNDEN 680000
#define MODE_PIN 2
#define UP_PIN 3
#define DOWN_PIN 4
enum MODE{ RUN, SET_HOUR, SET_MIN, SET_SEC };
enum MODE mode = RUN;

bool blink = false;
long hour = 0;
long minute = 0;
long second = 0;
long count_sec = 72000;

LiquidCrystal_I2C lcd(39,16,2);

void Timer1_Interrupt() 
{
  //Serial.println("*");  
  ++count_sec %= 86400;
}

//--------------------------------------------
void setup()
//--------------------------------------------
{
  Serial.begin( 9600 );
  pinMode( MODE_PIN, INPUT_PULLUP );
  pinMode( UP_PIN, INPUT_PULLUP );
  pinMode( DOWN_PIN, INPUT_PULLUP );
  lcd.init();
  lcd.backlight();
  lcd.setCursor(3,0);
  lcd.setCursor(3,1);
  lcd.print("Mode: "); 
  displayMode();
  Timer1.initialize(MICROSEKUNDEN);
  Timer1.attachInterrupt(Timer1_Interrupt);
}

//--------------------------------------------
void loop()
//--------------------------------------------
{
  checkAndChangeMode();
  if( mode == RUN )displayTime();
  else if(mode == SET_HOUR) hour   = setValue( hour,   24, 3, 0);
  else if(mode == SET_MIN)  minute = setValue( minute, 60, 6, 0);
  else if(mode == SET_SEC)  second = setValue( second, 60, 9, 0);
}

//--------------------------------------------
void checkAndChangeMode()
//--------------------------------------------
{
  if( digitalRead( MODE_PIN ) == LOW ){
    switch (mode){
      case RUN:      mode = SET_HOUR;           break;
      case SET_HOUR: mode = SET_MIN; setTime(); break;
      case SET_MIN:  mode = SET_SEC; setTime(); break;
      case SET_SEC:  mode = RUN;     setTime(); break;
      default:       mode = RUN;                break;
    }
	  displayMode();     
    delay( 150 );
  }
}

//--------------------------------------------
void displayMode()
//--------------------------------------------
{
  lcd.setCursor(9,1);
  lcd.print( mode );  
}
  
//--------------------------------------------
void calcTime(){
//--------------------------------------------
  hour = count_sec / 3600;
  minute = (count_sec - hour * 3600) / 60;
  second = count_sec % 60;
}  

//--------------------------------------------
void setTime(){
//--------------------------------------------
  count_sec = hour*3600 + minute*60 + second;
}
 
//--------------------------------------------
void displayTime()
//--------------------------------------------
{
  calcTime();
  dispTwoDigits( 3, 0, hour, ":");
  dispTwoDigits( 6, 0, minute,  ":");
  dispTwoDigits( 9, 0, second,  "");
}
  
//--------------------------------------------------------------
void dispTwoDigits( int x, int y, int number, String appendix )
//--------------------------------------------------------------
{
  lcd.setCursor(x,y); 
  if( number < 10 )lcd.print("0");
  lcd.print(number);
  lcd.print( appendix );
}

//--------------------------------------------------------------------
long setValue( long getValue, int devider, int xLcdPos, int yLcdPos )
//--------------------------------------------------------------------
{
  long value = getValue;
  if( digitalRead(UP_PIN) == LOW ){
    value = (value + 1) % devider;
    delay( 50 );
  }
  else if( digitalRead(DOWN_PIN) == LOW ){
    value = (value + devider - 1) % devider;
    delay( 50 );
  }
  if( blink ){ 
    dispTwoDigits( xLcdPos, yLcdPos, value, "");
  }else{
    lcd.setCursor(xLcdPos,yLcdPos);lcd.print("  ");
  }
  delay(100);
  dispTwoDigits( xLcdPos, yLcdPos, value, "");//don't leave value blank
  blink = !blink;  
  return value;
}


*/