Consider the following code: void loop() } . if (digitalRead(tiltSensorPin)) { // check if the pin is high digitalWrite(firstLEDPin, HIGH);// if it is high turn on firstLED digitalWrite( second LEDPin, LOW);// and turn off secondLED } else { // if it isn't digitalWrite( firstLEDPin, LOW);// do the opposite digitalWrite(secondLEDPin, HIGH);} }