avr-blink/blink.c

#include <avr/io.h>

#define F_CPU 20000000UL
#include <util/delay.h>

int main() {
	DDRB |= 1;

	while(1) {
		PORTB |= 1;
		_delay_ms(50);
		PORTB &= ~1;
		_delay_ms(950);
	}

	return 1;
}