#define LED 5

void setup() {
  pinMode(LED,OUTPUT);
  // put your setup code here, to run once:

}

void loop() {
  led_toggle(LED);
  delay(500);
  // put your main code here, to run repeatedly:

}

void led_toggle(int pin)
{
  int status = digitalRead(pin);
  digitalWrite(pin,!status);
}