access-register-1.ino

const int pin = 8;


void setup() 
{
    pinMode(pin, OUTPUT);

    volatile uint8_t* port = portOutputRegister(digitalPinToPort(pin));
    uint8_t mask = digitalPinToBitMask(pin);
    
    while (1) {
        *port ^= mask;
    }
}


void loop() 
{    
}