working_w_CTC_w_INTERRUPTION_w_OCRnx.c https://youtu.be/Umo5PFym7wM

working_w_CTC_w_INTERRUPTION_w_OCRnx.c

/* Project Ardu_Serie # 43
 * Working w/CTC w/Interruption w/ OCnx Toggle Pin Mode Part III - Atmega328p IC - Arduino MC
 *
 * Use: TIMER2 
 *
 * Objective: We need to flash an LED every 100 ms (10 Hertz).
 *            Using Interruption instead of polling technique!
 *            Getting hid of ISR Method! Use OCnx PIN (Toggle mode)
 */ 
#include <avr/io.h>
#include <avr/interrupt.h>        // include int library  

				  // initialize timer, interrupt and variable
void timer2_init()
{
				  // set up timer with prescaler = 1024 and CTC mode
	TCCR2A |= (1 << WGM21) | (0 << WGM20);
	
	                          // 1ª Modification: insert (1 << COM2A0)
	TCCR2B |= (1 << COM2A0) | (0 << WGM22) | (1 << CS22) | (1 << CS21) | (1 << CS20);	
   
   	TIMSK2 |= (1 << OCIE2A);  // enable CTC, Timer2, Ch A interruptions
		
	TCNT2 = 0;
				  // initialize compare value to 10 Hz
	OCR2A = 156;
	
	sei();                    // set Global Interrupt Enable;
				  // Arduino.h courtesy:)
}

                                  // 2ª Modification: Delete ISR altogether!
                                  // hence, toggle led here itself..
/*ISR (TIMER2_COMPA_vect)
{
	
	PORTB ^= (1 << PINB5);    // toggles the inbuild_LED - Arduino pin 13
}*/

int main(void)
{
				  //3ª Modification: connect led to pin PB3 - Arduino PIN D11
	DDRB |= (1 << PINB3);
	
				  // initialize timer
	timer2_init();
	
				  // loop forever (or never?)
	 while(1)
	   {
		                  // Nothing here :D
									
	   }
  }