Blink an LED light using an Arduino Uno


If you’re new to the world of electronics and programming, the Arduino Uno is a fantastic platform to start with. One of the simplest yet most exciting projects you can undertake is blinking an LED. It’s a great way to get familiar with the basics of coding and circuit building. In this blog post, we’ll guide you through the process of setting up your Arduino Uno and programming it to blink an LED using digital pin 8.

Materials Needed

Before we dive in, gather the following materials:

  • Arduino Uno board
  • LED (any color)
  • Resistor (220 ohms)
  • Breadboard
  • Jumper wires
  • USB cable for connecting the Arduino to your computer

Circuit Diagram

Here is a basic circuit diagram for an LED light using an Arduino Uno:

Step-by-Step Guide

1. Connecting the Components

First, let’s set up the physical components. Here’s a simple circuit diagram to follow:



  • Place the LED on the breadboard.
  • Connect the anode (the longer leg) of the LED to digital pin 8 on the Arduino using a jumper wire.
  • Connect the cathode (the shorter leg) of the LED to one end of the resistor.
  • Connect the other end of the resistor to the GND (ground) pin on the Arduino.

2. Setting Up the Arduino IDE

Next, we need to set up the Arduino Integrated Development Environment (IDE) on your computer:

  • Download and install the Arduino IDE.
  • Connect your Arduino Uno to your computer using the USB cable.
  • Open the Arduino IDE and select your board and port from the “Tools” menu:
    • Board: “Arduino Uno”
    • Port: Select the appropriate port that your Arduino is connected to.

3. Writing the Code

Now, let’s write the code to blink the LED. Open a new sketch in the Arduino IDE and enter the following code:

// Pin number where the LED is connected
const int ledPin = 8;

void setup() {
  // Initialize the digital pin as an output.
  pinMode(ledPin, OUTPUT);

void loop() {
  // Turn the LED on (HIGH is the voltage level)
  digitalWrite(ledPin, HIGH);
  // Wait for a second
  // Turn the LED off by making the voltage LOW
  digitalWrite(ledPin, LOW);
  // Wait for a second


  • const int ledPin = 8; defines the pin number connected to the LED.
  • pinMode(ledPin, OUTPUT); sets this pin as an output.
  • digitalWrite(ledPin, HIGH); turns the LED on.
  • delay(1000); waits for one second.
  • digitalWrite(ledPin, LOW); turns the LED off.
  • delay(1000); waits for one second.

The loop() function keeps repeating this sequence, making the LED blink on and off every second.

4. Uploading the Code

To upload the code to your Arduino:

  • Click the “Upload” button (right arrow icon) in the Arduino IDE. This will compile and transfer the code to your Arduino Uno.
  • Once the upload is complete, you should see the LED start blinking at one-second intervals.


If your LED isn’t blinking:

  • Double-check all the connections.
  • Make sure the correct board and port are selected in the Arduino IDE.
  • Verify the orientation of the LED (the longer leg should be connected to pin 8).


Congratulations! You’ve just completed your first Arduino project by making an LED blink. This simple project lays the groundwork for more complex projects involving sensors, actuators, and other components. Keep experimenting and exploring the exciting world of electronics with Arduino!

Feel free to share your experiences or ask questions in the comments below. Happy tinkering!

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