[avr-gcc-list] Issue with interrupt handler on Atmel Mega 8

[Jerome Kerdreux]

I'm trying to use the timer 0 on a mega 8.  Everything works fine, 
(I mean, i can see the timer TCNT0 incrementing) but when I want 
to route the interrupt to an handler, I get a infinite reset. 


Here a snipset of the code (full code, is attached) 

SIGNAL(SIG_OVERFLOW0)
{
  uptime ++;
  return 0;
}

void inittimer()
{
 // 1024 prescaler 
  sbi(TCCR0,CS02);
  cbi(TCCR0,CS01);
  sbi(TCCR0,CS00);

  // set the interrupt handle
  sbi(TIMSK,TOIE0);
  uptime = 0;
}



If I comment the sbi(TIMSK..) all works fine. What can I do to fix
that .? 


Thanks for any help.


/*
 * Author: Jerome Kerdreux, Copyright: GPL
 * 
 *
 * Chip type           : ATMEGA8
 * Clock frequency     : Internal clock 1 Mhz (factory default)
 */

#include <avr/io.h>
#include <avr/interrupt.h>
#include <stdlib.h> 
#include "test_avr.h"
#include "avr_compat.h"
#include "lcd.h"



#define TIMERINI 256-72
#define TIMERCON 0x05


volatile int uptime;



void delay_ms(unsigned short ms)
/* delay for a minimum of <ms> */
/* with a 1Mhz clock, the resolution is 1 ms */
{
	uint8_t inner,inner1;
    	while (ms) {
		inner = 100;
		while (inner) {
			inner--;
			inner1 = 70;
			while (inner1) {
				inner1--;
			}
		}
		ms--;
	}
}



void flashled()
{
  if bit_is_set(PORTD,PD5)  { cbi(PORTD,PD5); }
  else { sbi(PORTD,PD5); }
}



SIGNAL(SIG_OVERFLOW0)
{
  uptime ++;
  return 0;
}


void debug(char *msg)
{
  lcd_gotoxy(0,0);
  lcd_puts(msg);
  delay_ms(1000);
}


void inittimer()
{
 // 1024 prescaler 
  sbi(TCCR0,CS02);
  cbi(TCCR0,CS01);
  sbi(TCCR0,CS00);

  // set the interrupt handle
  //sbi(TIMSK,TOIE0);

  uptime = 0;
}



int main(void)
{
  char line[16];

  sbi(DDRD,PD5);

  lcd_init(LCD_DISP_ON);
  lcd_clrscr();

  debug("LCD Ok");

  // init the the timer 
  sprintf(line,"TCCR0 %x" , TCCR0);
  debug(line);
  inittimer();

  sprintf(line,"TCCR0 after %x" , TCCR0);
  debug(line);
  // 

  flashled();
  sei();
  debug("Sei Ok");
  while (1) 
    {
      delay_ms(500);
      lcd_gotoxy(0,0);
      sprintf(line,"Timer: %d     " , uptime);
      lcd_puts(line);

      lcd_gotoxy(0,1);
      sprintf(line,"TCNT0: %x " , TCNT0);
      lcd_puts(line);

      flashled();
    }
  
  return 0;
}

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