/*
// Blinking LED
void setup() {
  // initialize digital pin LED_BUILTIN as an output
  pinMode(LED_BUILTIN, OUTPUT);

}

void loop() {
  digitalWrite(LED_BUILTIN, HIGH);
  // turn on LED by making voltage level high
  delay(1000);
  digitalWrite(LED_BUILTIN, LOW);
  // turn off LED by making voltage level low
  delay(1000);
}

// Blinking External LED

/*Make connection such that UNO's GND to LEDs Cathode, Anode to Resistor, 2nd terminal of R to 13 
void setup() {
  pinMode(LED_BUILTIN, OUTPUT);
}
void loop() {
  digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(500);                       // wait for a second
  digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW
  delay(500);
}
*/

//Fading LED
#define LED_PIN 6 // must support PWM
#define FADE_SPEED 20 // lower is faster
void setup() {
  pinMode(LED_PIN, OUTPUT);
}
void loop() {
  for(int i = 0; i < 255; i++) {
    analogWrite(LED_PIN, i++);
    delay(FADE_SPEED);
  }
  for(int i = 255; i > 0; i--) {
    analogWrite(LED_PIN,i--);
    delay(FADE_SPEED);
  }
}