//write a code to blink leds one by one by pressing pushbutton 3 
//hardware is same as 1st exp

#define PINA   (*(volatile uint8_t*)0x20)
#define DDRA   (*(volatile uint8_t*)0x21)
#define PORTA  (*(volatile uint8_t*)0x22)

#define PINB   (*(volatile uint8_t*)0x23)
#define DDRB   (*(volatile uint8_t*)0x24)
#define PORTB  (*(volatile uint8_t*)0x25)

volatile uint32_t i,j;

void delay1sec(void){
    TCNT1  = 0;
    TCCR1A = 0x00;
    TCCR1B = 0x05;          // prescaler 1024
    while (TCNT1 < 15625);
    TCCR1B = 0x00;
}

int main(void){
    DDRA = 0xFF;      
    DDRB = 0x00;      

    while(1){
        if((PINB & 0x08) == 0x08){  
          for(j = 0; j<8; j++){
            PORTA = (1<<j);
            delay1sec();
            PORTA = 0x00;
            delay1sec();
          }

        } else {
            PORTA = 0x00;
        }
    }
}