外部中断0不起作用

Question

Can anybody figure out why my external interrupt 0 doesn't work? I am using an AVR STK 500 board with an ATmega164P on it. Is it because the pin D2 has got two functions?

#include <asf.h>
#include <avr/interrupt.h>
#include <avr/io.h>

#define F_CPU 8000000UL
#include <util/delay.h>

ISR(INT0_vect)
{
    PORTB = 1;
    for(int i = 0; i < 7; i++)
    {
        _delay_ms(500);
        PORTB << 1;
    }
}

int main (void)
{
    board_init();

    sei();

    PORTD = 0xFF;
    DDRD = 0x00;
    PORTB = 0x00;
    DDRB = 0xFF;

    while(1)
    {
        PORTB = PIND;
    }
}

Answer 1

I guess you don't enable the external interrupt.

Look at the data sheet section 10.2.

10.2.2 EIMSK – External Interrupt Mask Register

When an INT2:0 bit is written to one and the I-bit in the Status Register (SREG) is set (one), the corresponding external pin interrupt is enabled. The Interrupt Sense Control bits in the External Interrupt Control Register, EICRA, defines whether the external interrupt is activated on rising or falling edge or level sensed.

So you have to set

EIMSK |= (1 << INT0);

to enable INT0 and potentially EICRA to define what signal edge you want to react at.