Arduino101.ino

#define LED_PIN 13
#define BUTTON_PIN 2
#define DIM_LED 11

void setup() {
  pinMode(LED_PIN, OUTPUT);
  pinMode(DIM_LED, OUTPUT);
  pinMode(BUTTON_PIN, INPUT);
}

void loop() {
  if (digitalRead(BUTTON_PIN) == HIGH) {
    analogWrite(DIM_LED, 50);
  }
  else {
    analogWrite(DIM_LED, 255);
  }
}