gicutabacaru 
I made this program to turn on some lights on PORTC on mY Atmega8535.There's a button on PORTD, pin4 (counting from 0), but it has no effect when I press it.Can you help me please? thank you.
(i'm using programmers notepad)
#include
#include
int main(void)
{
DDRC = 0xFF;
PORTC = 0x00;
DDRD = 0x00;
PORTD = 0xFF;
while(1)
{
if ((PIND & 0x0F))
{
PORTC = ~PORTC;
}
}
return(0);
}
clawson 
"PIND & 0x0F" means read the 8 bit value currently presented at PIND and then set the top 4 bits to 0. as the bit you are trying to "watch" is in this region you are just throwing away it's current value by doing the test this way. Try:
if (PIND & (1<<PD4)) {
PORTC = ~PORTC;
}
and then mosey on down to the Tutorial section here and read the thread that has "101" in the title!
Cliff
oshaker you might want to add some delay in order to note the blinking LEDs...
#include..... ..... ..... ..... if (PIND & (1<<PD4)) { PORTC = ~PORTC; _delay_ms(20); }
gicutabacaru worked fine :), thank you very much