const int POT_PIN = A0; 
const int LED_PIN = 3;  
const int SET_THRESHOLD = 512;

void setup() {
  pinMode(LED_PIN, OUTPUT); 
}

void loop() {
  int analogValue = analogRead(POT_PIN); 

  if(analogValue > SET_THRESHOLD)
    digitalWrite(LED_PIN, HIGH); 
  else
    digitalWrite(LED_PIN, LOW);
}