This exercise is the same as the previous one with the only difference that a led connected to pin 13 is used instead of using the built-in led.

// define constants
const int led_pin = 13;

// initialisation
void setup()
{
    // set the digital pin as output
    pinMode(led_pin, OUTPUT);
}

// main loop function
void loop()
{
    digitalWrite(led_pin, HIGH); // turn the LED on
    delay(1000);                 // wait for a second
    digitalWrite(led_pin, LOW);  // turn the LED off
    delay(1000);                 // wait for a second
}

1. Connect the External LED:

   • Connect the anode of an LED to digital pin 13 on the Arduino.
   • Use appropriate resistors (e.g., 220Ω) in series with the LED to limit current.
   • Connect the cathode of the LED to the GND rail.

2. Upload the Arduino Code:

   • Copy the provided code for blinking the LED.
   • Open the Arduino IDE, paste the code, and upload it to the Arduino.

3. Observe LED Behaviour:

   • The external LED connected to pin 13 will turn ON for one second and OFF for one second in a continuous loop.
   • Modify the delay() values in the code if you wish to change the blinking speed.

4. Experiment and Modify:

   • Try connecting the LED to a different pin and update the led_pin value in the code accordingly.
   • Experiment with different delay durations to observe variations in blinking speed.