#define POTENTIOMETER_PIN 4
#define LED_PIN           15
#define ANALOG_THRESHOLD  250
void setup() {
  
  analogSetAttenuation(ADC_11db);
  pinMode(LED_PIN, OUTPUT); 
}

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

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