Electronic – Setting external oscillator for atmega328p

atmegacrystal

I'm trying to use a 8MHz Oscillator on an atmega328p. this a part of the whole schematic :

enter image description here

to that I've set the Fuse byte as calculated
enter image description here[2]

then I've set the calculate values in the project :

enter image description here

To make sure that the uc ist correctly runnion on 8MHz, since I don't have an oscilloscope, I'm trying to toggle a LED each 1 sec, here is the code I've wrote for that : 

#define F_CPU 8000000
#include <avr/io.h>
#include <util/delay.h>
int main(void)
{

DDRD |= (1 << PD5); 
    while(1){
        PORTD |= (1 << PD5);  
        _delay_ms(1000);     
        PORTD &= ~(1 << PD5);
        _delay_ms(1000);     
    }
    return 0;
    }

As far as I can see the lED take 8sec to change its status ! when I change the value of F_CPU to 1MHz the toggle is than correct, which means to me that I'm still running the internal oscillator ?

Any idea what I'm missing here ?
thanks in advance !

Best Answer

You checked the divided by 8 fuse bit. So the CPU runs at 8mhz/8. Uncheck it.

Related Topic