//  DvalleyElectronics  sharing  knowledge   for public domain   
//  Emanuel Cesar Dec/2018
#define NOP asm("nop")
#define BLACK    PORTB = B00000000;
#define BLUE     PORTB = B00000001;
#define GREEN    PORTB = B00000010;
#define CYAN     PORTB = B00000011;
#define RED      PORTB = B00000100;
#define MAGENTA  PORTB = B00000101;
#define YELLOW   PORTB = B00000110;
#define WHITE    PORTB = B00000111;

unsigned int counterlines = 1;

void setup()
{
  //Sets  pins 5, 6 , 7 ,8  and 9 outputs
  // 7 - HSYNC
  // 6 - VSYNC
  // 5 - R  
 //  8 - G
 //  9 - B 
  
  
  DDRD |= B11100000;
  DDRB |= B11100111;
  PORTD |= B11000000;

                                                       //set timer  
  TCCR2A = 0x02;                        // WGM22=0 + WGM21=1 + WGM20=0 = Mode2 (CTC)
  TCCR2B |= (1 << CS20);             // 
  TCCR2B |= (1 << CS21);             // Sets prescaler
  TCCR2B &= ~(1 << CS22);            //
  
  TCNT2 = 0;                                // clear th counter
  //OCR2A = 0x03;                         // sets counter  to comp

  TIMSK2 &= ~(1<<OCIE2A);                // sets interrupt for comp  
  TIMSK2 |= (1<<TOIE2);                // sets interrupt for overflow  
}

void loop()
{
  noInterrupts();
  do{
    BLACK;
    if (TCNT2 > 0x0f){

      delayMicroseconds(1); 
      NOP;NOP;NOP;NOP;
      
      TCNT2 = 0x00;

    
                     
                                                                                           // #### HSYNC ###
      PORTD &= ~(1 << 7);      
      if (++counterlines >= 525){                                       //    525 OR 625 scan lines... just 483 lines can be seen 
        counterlines = 1;
      }      
      PORTD |= (1 << 7);



      // ### VSYNC ###
      if ((counterlines == 1)||(counterlines == 2)){                                               //                          492 e 493
        PORTD &= ~(1 << 6);      
      } else {
        PORTD |= (1 << 6);
        

        NOP;NOP;NOP;NOP;NOP;NOP;NOP;NOP;NOP;NOP;
        NOP;NOP;NOP;NOP;NOP;NOP;NOP;NOP;NOP;NOP;
        NOP;NOP;NOP;NOP;NOP;NOP;NOP;NOP;NOP;NOP;
        NOP;NOP;NOP;NOP;NOP;
        
        if ((counterlines >= 9) && (counterlines <= 489)){                                                        //                                 2 e 482
          
                WHITE;
                delayMicroseconds(3);NOP;NOP;NOP;NOP;NOP;NOP;NOP;NOP;
                BLACK;
                delayMicroseconds(3);NOP;NOP;NOP;NOP;NOP;NOP;NOP;NOP;
                BLUE;
                delayMicroseconds(3);NOP;NOP;NOP;NOP;NOP;NOP;NOP;NOP;
                GREEN;
                delayMicroseconds(3);NOP;NOP;NOP;NOP;NOP;NOP;NOP;NOP;
                CYAN;
                delayMicroseconds(3);NOP;NOP;NOP;NOP;NOP;NOP;NOP;NOP;
                RED;
                delayMicroseconds(3);NOP;NOP;NOP;NOP;NOP;NOP;NOP;NOP;
                MAGENTA;
                delayMicroseconds(3);NOP;NOP;NOP;NOP;NOP;NOP;NOP;NOP;
                YELLOW;
                delayMicroseconds(3);NOP;NOP;NOP;NOP;NOP;NOP;NOP;NOP;
                BLACK;
                NOP;NOP;NOP;NOP;
        }
            
      }
}


}while(1);

}