#include <avr/io.h>

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

int buttonState = 0;

int main(void)
{
	CPU_CCP = CCP_IOREG_gc; // Un-protect protected I/O registers - allow clock changes
	CLKCTRL_MCLKCTRLB = 0; // disable clock prescaler - clock is now equal to system clock - 20MHz
	
    VPORTA_DIR |= PIN7_bm;
    VPORTA_IN |= PIN4_bm;
	
	while(1)
    {
        buttonState = VPORTA_IN & PIN4_bm; 
        // If button is not pressed
        if (buttonState > 0) {
    		PORTA_OUTTGL = PIN7_bm;  // Toggle PORTB pin 0
	    	_delay_ms(1000); // gives a 1 Hz toggle rate
	    }
	}
}