AVR Freaks

Dear Community

I started a small INT0 exersise.

Thats what the code should do:

I apply 100Hz signalto INT0 pin

I declared a variable uinit32_t counter.

In the ISR I increment the counter by 1.

In a while loop I check if counter exceeds 1000 counts and if yes I toggle pin4 of portD.

I checked with a pin toggle in the ISR that the interrupt gets sensed and it does. I have just wondered about the quite long latency of ca. 3us until the interruppt gets serviced.

The debuger does not help much, when I do single step it goes straight to the PORTD toggle (after initialising) after executing PORTD toggle it goes to "if (counter >= 1000)" and the debugger exits single stepping, I can only stop or pause.

It looks like a simple code,buit I dont know whats wrong.

Have you got a tip?

regards

Juergen

/*
 * ExternInt0.c
 *
 * Created: 18.10.2019 10:36:28
 * Author : jb
 */ 

#include <avr/io.h>
#include <avr/interrupt.h>
//uint8_t counter;
uint32_t counter;

ISR (INT0_vect)
{
	counter++;
	//PORTD ^= (1<<4);
}

int main(void)
{
	
    DDRD &= ~(1<<PD2);
	DDRD |= (1<<PD4);
	PORTD = 0x00;
	
	EICRA |= (1<<ISC01) | (1<<ISC00);
	EIMSK |= (1<<INT0);
	
	sei();
	   
	while (1) 
    {
		if (counter >= 1000)
		{		
			PORTD ^= (1<<4);
			counter= 0;	
		}
		
    }
}