#define dialPin  2 
#define redLED   4
#define greenLED 3

bool checkPin ( int *input, int *truePin );

bool keep_count = 1;
int  Pindex     = 0;
volatile int Cycle = 0;
volatile int Tick  = 0;

int inputPin[5] = { 0, 0, 0, 0, 0}; //we add an extra element to avoid buffer overflow
int truePin [4] = { 1, 7, 3, 8};

void setup() {

    pinMode (dialPin, INPUT);
    pinMode (redLED , OUTPUT);
    pinMode (greenLED,OUTPUT);
    pinMode ( 11, OUTPUT);
    digitalWrite(11, LOW);

    noInterrupts();
    TCCR2A = 0; // Timer/Counter ContRol Registers used to set mode, prescalar, other options
    TCCR2B = 0;  

    TCCR2B |= ( 1 << CS22); // we set the Clock Select bit of this register so that our prescalar is 64
    // desired f = 1000 Hz
    // Clock Speed /( prescaler * ( counter max - start of count ) ) = f
    // 16 000 000 / ( 64 * ( 256 - x ) )  = 1000 Hz
    // x = 6
    TCNT2  = 6; // Timer CouNTer register. This is what is incremented.  We start OUR specific count at 48

    TIMSK2 = 0;
    TIMSK2 |= ( 1 << TOIE1 ); // on the Timer Interrupt Mask Register   the  TimerOverflowInteruptEnable bit is set
 
    Serial.begin (9600);
    
}


//IMPORTANT NOTE: with an 8 bit counter running with a prescalar of 64 and an initial count of 6 we get about 1000Hz
//So we want 3 seconds at 1000 cycles per second = MAX_CYCLES of 3000
//For a debounce of 50ms we likewise need 75 cycles 

#define MAX_CYCLES 1500 //for 1.5 seconds
#define MAX_WAIT   20 // for 20 ms debounce
void loop()
{
  
  Pindex = 0;

  digitalWrite ( redLED, HIGH );
  digitalWrite ( greenLED, LOW);
  while ( Pindex < 4 )
  {
      noInterrupts();
      Cycle     =  0;
      keep_count =  1;
      
          if ( digitalRead(dialPin) == HIGH )
          {

              interrupts();
              //inputPin [Pindex] ++;
              //wait_a_tick(1);

              while ( Cycle < MAX_CYCLES )
              {
                  if ( keep_count && digitalRead( dialPin ) == HIGH)
                  {
                      inputPin [Pindex] += 1;
                      keep_count = 0;  
                      wait_a_tick(1);
                  }

                  else if ( digitalRead ( dialPin ) == LOW )
                  {
                      keep_count = 1; 
                      wait_a_tick(1);
                  }
                  
              }

              noInterrupts();
              TCNT2  = 0;
              Pindex ++;
              
              
            }

            Serial.print(inputPin [0] );Serial.print(inputPin [1] );
              Serial.print(inputPin [2] );Serial.print(inputPin [3] );
              Serial.print("\n");
  }

  if ( checkPin ( inputPin, truePin ) )// Lets check to see if our pin number is right
  {
       digitalWrite ( redLED, LOW );
       digitalWrite ( greenLED, HIGH);

       interrupts();
       wait_a_tick(100 ); //1 tick = 20ms so 2 seconds = 100 ticks
  }

  memset ( inputPin, 0, sizeof(inputPin)); // we reset the entered pin to zero
}


///////////////////////////////////

bool checkPin ( int *input, int *truePin )
{
    bool pinCorrect = 1;
    
    for ( int i = 0; i < 4; i ++ )
    {
        if ( (*(input + i)) != (*(truePin + i)) )
        {
            pinCorrect = 0;  
        }      
    }  

    return pinCorrect;

}
/////////////////////////////////////////
void wait_a_tick (int ticks)
{
  for ( int tocks = 0; tocks <= ticks; tocks ++)
  {
     Tick = 0;
     while ( 1 == 1 )
     {
        if ( Tick >= MAX_WAIT )
        {
            break;
        }
      }
  }
      return;
}



///////////////////////////////////////////////////
ISR(TIMER2_OVF_vect)          // timer compare interrupt service routine
{
  Cycle ++;
  Tick  ++;
}