day00/ex03/main.c

#include <avr/io.h>
#include <util/delay.h>

#include <stdbool.h>

#define LED_PORT PORTB0
#define BTN_PORT PIND2

int main(void) {
	// set pin to output
	// DDRB is the register that set the direction of the pins (IN/OUT)
	// we want to say that the LED_PORT pin is an OUT pin, which isnt the default
	DDRB		  |= (_BV(LED_PORT));

	// lets keep track of the led state here
	bool led_state = false;
	// lets also keep track of the button state for the last iteration
	bool prev	   = (PIND & _BV(BTN_PORT));
	while (true) {
		// we read it
		bool cur = (PIND & _BV(BTN_PORT));

		// if it wasnt pressed before, but pressed now -> it just turned on
		if (prev && !cur) {
			// toggle the state and update the led with the new state
			led_state = !led_state;
			if (led_state)
				PORTB |= (_BV(LED_PORT));
			else
				PORTB &= ~(_BV(LED_PORT));
		}
		// keep track of the old state for next iteration
		prev = cur;
		// sleep
		_delay_ms(20.f);
	}
}