Confusion about none working Interrupt 2 on a ATMega644P/1284P

Other Hardware 3rd Party Boards
6

Hi Steve,

By core I meant the Arduino "core" code ... I'm using maniacbug's mighty-1284p core.

Anyway the following sketch works fine for INT0, 1 or 2. I'm just using a 1Hz square wave from an RTC as the signal to the interrupt pin, and toggling an LED.

const uint8_t ledPin = 7;

void setup(void)
{
    pinMode(ledPin, OUTPUT);
    attachInterrupt(2, intHandler, FALLING);
}

void intHandler(void)
{
    static bool ledState;
    
    digitalWrite(ledPin, ledState = !ledState);
}

void loop(void)
{
}