atmega4809_cnano_blink.c

#include <avr/io.h>
#define F_CPU 3333333UL // 20 MHz / 6
#include <util/delay.h>
 
// F5 is the yellow LED
// F6 is the user switch
 
int main(void) {
 
  PORTF.DIRSET = _BV(5);
 
  while (1) {
    PORTF.OUTTGL = _BV(5);
    _delay_ms(1000);
  }
  return 0;
}