int db3 = 1;
int db5 = 0;
int db6 = 1;
int db7 = 0;
int cb2;
int cb1;
int cb4;
int frame[11];
int data[4][4] = {
                   {0,0,1,0},
                   {0,1,1,0},
                   {1,0,1,0},
                   {1,1,0,1},
                   
                   };
int state=0;

int duration=500;
int buttonPin = 2;
int buttonPin2 = 4;
int buttonPin3 = 6;
int buttonPin4 = 7;
int buttonValue;
int buttonValue2;
int buttonValue3;
int buttonValue4;
int m= -1;
void setup() {
  
  pinMode(13, OUTPUT);
  pinMode(8, OUTPUT);

  digitalWrite(8, LOW); 


  

  pinMode(buttonPin , INPUT);
  pinMode(buttonPin2, INPUT);
  pinMode (buttonPin3 , INPUT);
  pinMode (buttonPin4 ,INPUT);
   

}

void loop() {
  if ( m != -1)
  {
  switch (state)
  { 
    case 0:
        state = 1;
        break;
    case 1:
        digitalWrite(8, HIGH);
        delay(duration*5);
        state = 2;
        break;
    case 2:
        findCB(m);
        createFRAME(m);
        sendFRAME();
        digitalWrite (8, LOW);
        state=0;
        m=-1;
        break;
  }
  }

 buttonValue = digitalRead (buttonPin);

 if (buttonValue == HIGH)
 {
  digitalWrite (13,HIGH);
  m= 0;
 }
 {

buttonValue2 = digitalRead (buttonPin2);
 if (buttonValue2 == HIGH)
  m= 1;

 buttonValue3 = digitalRead (buttonPin3);
  if (buttonValue3 == HIGH)
  m=2;
  
buttonValue4 = digitalRead (buttonPin4);
  if (buttonValue4 == HIGH)
  m=3;
  
 }
  
}

void findCB(int row)
{  
  int count = 0;

  if (data[row][0] == 1) count++;
  if (data[row][1] == 1) count++;
  if (data[row][3] == 1) count++;

  if (count == 0 || count == 2)
      cb1 = 0;
  else
      cb1 = 1;

  count = 0;

  if (data[row][0] == 1) count++;
  if (data[row][2] == 1) count++;
  if (data[row][3] == 1) count++;

   if (count == 0 || count == 2)
      cb2 = 0;
  else
      cb2 = 1;

 count=0;

  if (data[row][1]== 1) count++;
  if (data[row][2] == 1) count++;
  if (data[row][3] == 1) count++;

   if (count == 0 || count == 2)
      cb4 = 0;
  else
      cb4 = 1;
}

void createFRAME(int row)
{
  frame[0]= 0; // preample bits 0101
  frame[1]= 1;
  frame[2]= 0;
  frame[3]= 1;
  frame[4]= cb1;    // control and data bits
  frame[5]= cb2;
  frame[6]= data[row][0];
  frame[7]= cb4;
  frame[8]= data[row][1];
  frame[9]= data[row][2];
  frame[10]= data[row][3];

}

void sendFRAME ()
{
  for (int i=0; i<= 10; i++)
  { digitalWrite (8, frame [i]);
    delay (duration);
    
    }
  
  }