void setup() 
{
    pinMode(4, OUTPUT);     // «Å§i4¬°¿é¥X
}

void loop() 
{
    digitalWrite(4,HIGH);       // turn the LED on
    delay(1000);                    // wait for a second
    digitalWrite(4,LOW);        // turn the LED off 
    delay(1000);                    // wait for a second
}