Does Arduino Nano Have a Built-In LED?



Arduino Nano is a popular choice among electronics enthusiasts for its compact size and versatility in various projects. One common question that often arises, especially among beginners, is whether the Arduino Nano has a built-in LED. In this article, we’ll explore the answer to this question and provide you with essential information about the Arduino Nano’s hardware and features.

Arduino Nano Overview:

Before delving into the presence of a built-in LED, let’s have a brief overview of the Arduino Nano.

Arduino Nano is a miniature-sized microcontroller board that is based on the ATmega328P microcontroller. It’s part of the Arduino family and offers similar capabilities to its larger counterparts, such as the Arduino Uno. Despite its small size, the Arduino Nano is a powerful and versatile board that can be used in a wide range of electronic projects.

Built-In LED on Arduino Nano:

Yes, the Arduino Nano does come with a built-in LED. This LED is often referred to as the “onboard” or “built-in” LED and is labeled as “L” on the board itself.

The onboard LED on the Arduino Nano serves multiple purposes, making it a handy feature for both beginners and experienced users. Here are some of its primary functions:

1. Power Indicator:

  • The built-in LED on the Arduino Nano serves as a power indicator. When you connect the Nano to a power source, such as a USB cable or an external power supply, this LED will light up. It indicates that the board is receiving power and is ready for operation.

2. Pin 13 Indicator:

  • The “L” LED is connected to digital pin 13 on the Arduino Nano. You can control this LED in your sketches by writing code to turn it on or off. It’s an excellent way to test basic functionality and learn about digital output in Arduino programming.

3. Debugging Tool:

  • The onboard LED can also be a valuable tool for debugging your projects. You can use it to visually confirm whether certain parts of your code are executing correctly. For example, you might use it to check if a specific section of your program is running or to monitor sensor inputs.

How to Control the Onboard LED:

Controlling the onboard LED on the Arduino Nano is straightforward. Here’s a simple example of how to turn the LED on and off in an Arduino sketch:

arduinoCopy code

void setup() { // Set pin 13 (connected to the onboard LED) as an OUTPUT pinMode(13, OUTPUT); } void loop() { // Turn the LED on digitalWrite(13, HIGH); delay(1000); // Wait for 1 second // Turn the LED off digitalWrite(13, LOW); delay(1000); // Wait for 1 second }

In this example, we use the pinMode function to set pin 13 as an OUTPUT, and then we use digitalWrite to turn the LED on (HIGH) and off (LOW) with a one-second delay between each state change.


In summary, the Arduino Nano indeed has a built-in LED labeled as “L.” This LED serves as a power indicator, a tool for learning digital output, and a useful aid for debugging your projects. Understanding how to control the onboard LED is a fundamental skill for anyone working with Arduino Nano, and it opens the door to more complex projects and creative applications in the world of electronics and programming.

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