day00/ex02/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));

	while (true) {
		// to read the pin value (IN pin), we read from the PINX register, and
		// select the correct bit. Here the correct bit is the 1 << BTN_PORT1
		bool cur = (PIND & _BV(BTN_PORT));

		// depending on if the pin is set, we turn on or off the led
		if (!cur)
			PORTB |= (_BV(LED_PORT));  // on
		else
			PORTB &= ~(_BV(LED_PORT));	// off

		// lets wait a bit before going again
		_delay_ms(20.f);
	}
}