ok…
seee here
PORTD|= (1<<PD0);
_delay_ms(1000);
PORTD| = (0<<PD0);
ur dng OR operation, means applying LOGICAL OR.
that mean dng 1 ORING with 0….
again the result also 1.
that is the reason….
and one more suggetn is give delay after clearing PD0
means
PORTD|= (1<<PD0);
_delay_ms(1000);
PORTD| = (0<<PD0);
_delay_ms(1000);
k?