void setup() {
  DDRC |= _BV(0) | _BV(1) | _BV(3);
  PORTC=0x00;
}
void loop()
{
  long a;
  for(a = 0; a < 128; a+= 1)
  {

    PORTC &= ~( _BV(3));
    shiftOut(a);
    PORTC |= ( _BV(3));
  }
  for(a = 128; a > 0 ; a-= 1)
  {
    PORTC &= ~( _BV(3));
    shiftOut(a);
    PORTC |= ( _BV(3));
  }
}




void shiftOut(long myDataOut)
{
  int pinState;
  PORTC &= ~( _BV(0));
  PORTC &= ~( _BV(1));
  int outPut;
  for (outPut=0; outPut < 24; outPut++)  //24 different outputs
  {
    for(int val = 11; val >= 0; val--)    //12 bit number
    {
      PORTC &= ~( _BV(1));
      if ( myDataOut & (1<<val) )
      {
        pinState = 1;
        PORTC |= ( _BV(0));
      }
      else
      {
        pinState= 0;
        PORTC &= ~( _BV(0));
      }

      PORTC |= ( _BV(1));
      PORTC &= ~( _BV(0));
    }
  }
  PORTC &= ~( _BV(1));
}