How to Make a Simple Arduino Traffic Light Controller With Blynk App

How to Make a Simple Arduino Traffic Light Controller With Blynk App


Controlling traffic lights with an Arduino is a fun electronics project that allows you to learn about microcontrollers and internet of things (IoT) applications. With just a few electronic components and free software, you can make your own traffic light controller that can be monitored and controlled from your smartphone.

In this guide, I will show you how to build a simple traffic light controller using an Arduino Uno board, an RGB LED module, resistors, jumper wires, and the Blynk app. I will cover how to connect the circuit, program the Arduino, and set up the Blynk app interface step-by-step. By the end, you will have a working traffic light prototype controlled from your phone!

What You Will Need

To build the Arduino traffic light controller, you will need:

Circuit Diagram

Here is the circuit diagram for connecting the RGB LED module to the Arduino:

The main components are:

Setting Up the Circuit

Follow these steps to set up the circuit on your breadboard:

  1. Insert the RGB LED module into the breadboard. The long leg of each LED connects to a digital pin on the Arduino.

  2. Connect the short legs of the LEDs (the common cathode) together and then to the Arduino ground.

  3. Place a 220Ω resistor in series with each of the long LED legs to limit the current.

  4. Connect digital pins 6, 5, and 3 from the Arduino to the resistors.

  5. Connect the Arduino ground to the breadboard rails.

  6. Double check that all component legs are inserted securely into the breadboard holes.

The traffic light LEDs are now ready to be controlled by the Arduino!

Loading the Arduino Program

The Arduino needs to be programmed with code to control the LEDs and communicate with the Blynk app. Here are the steps:

  1. Download the Arduino IDE software on your computer.

  2. Open the example sketch Blynk_Traffic_Light.ino from the File > Examples > Blynk menu.

  3. Update the sketch with your WiFi network name and password, and the Auth Token from your Blynk app project (explained later).

  4. Connect the Arduino to your PC with the USB cable. Select the board type and COM port.

  5. Verify and upload the sketch to the Arduino.

Now the Arduino is running the code to handle the app button presses and drive the LEDs!

Setting Up the Blynk App

The free Blynk app allows you to create interfaces and control hardware remotely over the internet. Here's how to set it up for the traffic light:

  1. Download the Blynk app on your iOS or Android device.

  2. Create an account and log into the app.

  3. Create a New Project and give it a name like "Traffic Light".

  4. Add three Button widgets, color them red, yellow, and green, and rename them appropriately.

  5. Arrange the buttons vertically to mimic a traffic light.

  6. Deploy the project to get the Auth Token to connect the app to the Arduino.

That's it! You should now be able to press the buttons and see the indicator LEDs change on the Arduino side.

How it Works

Here is a brief overview of how the components work together:

So in summary, the Blynk app provides wireless control to easily switch the Arduino pins and LEDs on and off!

Optional Enhancements

Some ideas for enhancing this basic prototype:

The possibilities are endless for creating more advanced traffic light systems!


Building your own Arduino traffic light controller is an enjoyable electronics project that teaches useful IoT and microcontroller skills. With simple components like an Arduino, breadboard LEDs, and the Blynk mobile app, you can construct a working traffic light model that is wirelessly controllable from your smartphone.

Start with the basics as covered in this guide, then expand on the concept by trying out some of the suggested enhancements. Be creative and have fun experimenting to make your own unique Arduino traffic light system!