//connnect led to port j bit 0 blink it with 1 sec delay
#include <stdint.h>

#define DDRJ  (*(volatile uint8_t*)0x104)
#define PORTJ (*(volatile uint8_t*)0x105)

void delay1sec(void){
    TCNT1  = 0;
    TCCR1A = 0x00;
    TCCR1B = 0x05;      

    while (TCNT1 < 15625);

    TCCR1B = 0x00;      
}

void setup() {
    DDRJ |= (1 << 0);   
}

void loop() {
    PORTJ |= (1 << 0);  
    delay1sec();

    PORTJ &= ~(1 << 0); 
    delay1sec();
}