[SOLVED] AVR microcontroller delay problem

[irfan ahmad]

I am trying to toggle PORTC of atmega16 at rate of
100ms.
this is my code .

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

  DDRC=0XFF;
  PORTC=0XFF;

  while(1)
{	
  	 _delay_ms(100);
     PORTC=~PORTC;
   }
  return 0;
}
////////////////////////

these are simulation results on proteus.
it toggles after32ms.
what is problem.

 

[kripacharya]

Which pin are you measuring this on ? PORTC pins have many alternate functions, and there may be some conflict somewhere.

Try toggling just one bit, which is not too critical of its alternate functions.

 

[irfan ahmad]

i am measuring on C0.
if i am just toggling PORTC then i can measure from any pin.
am i right?
also i have tested this code

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

  DDRC=0XFF;
  PORTC=0XFF;

  while(1)
{	
  	 _delay_ms(250);
  	 _delay_ms(250);
  	 _delay_ms(250);
  	 _delay_ms(250);
  	 PORTC=~PORTC;
   }
  return 0;
}

with these fuse settings L=0XE4 , H=0XF9.
using genius programmer G540

It is flashing led very fast. less then 250ms.
please guide me .
currently i am trying to enable internal oscillator at 8Mhz.

 

[PA3040]

Hi

Tray to disable JTAG and try

 

[irfan ahmad]

Thank mr PA3040 and kripacharya .
Problem is solved by your help and this webpage
https://www.engbedded.com/fusecalc