#define RED_LED_PIN 11
#define POTENCIOMETER_PIN A0
#define ONE_SECOND 1000

void setup() {
  pinMode(RED_LED_PIN, OUTPUT);
  pinMode(POTENCIOMETER_PIN, INPUT);

  Serial.begin(9600);
}

void loop() {
  int potValue = analogRead(POTENCIOMETER_PIN); // 0 - 1023 (0v - 5v)
  int ledLum = map(potValue, 0, 1023, 0, 255);
  analogWrite(RED_LED_PIN, ledLum); // 0 - 255 (0v 5v)
}