#include <avr/io.h>

#define SET(REGISTER, BIT)		REGISTER |= 1 << BIT
#define CLEAR(REGISTER, BIT)	REGISTER &= ~(1 << BIT)
#define TEST(REGISTER, BIT)		REGISTER & 1 << BIT
#define TOGGLE(REGISTER, BIT)	REGISTER ^= 1 << BIT

int main()
{
    // DDRx : select direction of the pin
    //      - 1 = output (pull-up off)
    //      - 0 = input
    // PORTx :
    //      if DDRx = 1 (output mode) :
    //      - 1 = HIGH (5V)
    //      - 0 = LOW (0V)
    //      if DDRx = 0 (input mode) : 
    //      - 1 = pull-up on
    //      - 0 = pull-up off
    // PINx : 


    // turn on led 1
    SET(DDRB, 0);		// make PB0 as OUTPUT
    SET(PORTB, 0);		// make PB0 as HIGH (LED turns ON)

    // CLEAR(DDRB, 1);		// make PB0 as INPUT
    // SET(PORTB, 1);		// make PB0 pullup on

    // SET(DDRB, 2);		// make PB0 as OUTPUT
    // CLEAR(PORTB, 2);		// make PB0 as LOW (LED turns OFF)

    // CLEAR(DDRB, 4);		// make PB0 as INPUT
    // CLEAR(PORTB, 4);		// make PB0 as LOW (LED turns OFF)

    return 0;
}