Arduino Web Server Control Relay


In this article, we will explore how to control a relay using an Arduino web server. A relay is an electrical switch that allows you to control a high-power circuit with a low-power signal. By connecting a relay to an Arduino board and creating a web server, you can remotely control devices such as lights, fans, or even appliances over the internet.

Components Needed

To build an Arduino web server control relay, you will need the following components:

1. Arduino Board

The heart of the project is an Arduino board, which acts as the microcontroller. You can use any Arduino board, such as Arduino Uno or Arduino Mega, depending on your requirements.

2. Ethernet Shield

An Ethernet shield is required to enable the Arduino to connect to the internet. It allows the Arduino to communicate with other devices using the TCP/IP protocol.

3. Relay Module

A relay module is essential for controlling high-power devices. It provides isolation between the Arduino and the high-voltage circuit, ensuring safety.

4. Jumper Wires

Jumper wires are used to connect the components together. They come in various lengths and colors, making it easier to create the required connections.

Circuit Diagram

Before we proceed, let’s take a look at the circuit diagram for the Arduino web server control relay project.

Step-by-Step Instructions

Step 1: Setting Up the Hardware

Start by connecting the Ethernet shield to the Arduino board. Ensure that the pins are aligned correctly and firmly inserted. Next, connect the relay module to the Arduino using jumper wires. Make sure to connect the appropriate relay control pins to the Arduino’s digital pins.

Step 2: Installing Required Libraries

To create a web server, we need to install the necessary libraries. Open the Arduino IDE, go to “Sketch”> “Include Library”> “Manage Libraries.” Search for the “Ethernet” library and click “Install.” Similarly, install the “SPI” library if it’s not already installed.

Step 3: Writing the Code

Now, let’s write the code for the Arduino web server control relay. Open a new sketch in the Arduino IDE and copy the following code:

Step 4: Uploading the Code

Connect the Arduino board to your computer using a USB cable. Select the appropriate board and port from the “Tools” menu in the Arduino IDE. Then, click the upload button to upload the code to the Arduino board.

Step 5: Testing the Web Server

Once the code is uploaded successfully, open the Serial Monitor in the Arduino IDE. It will display the IP address assigned to the Arduino by your local network. Note down this IP address for future reference.

Now, open a web browser on any device connected to the same network as the Arduino. Enter the Arduino’s IP address in the address bar and press Enter. The web server should load, displaying a simple interface to control the relay.

Step 6: Controlling the Relay

Using the web interface, you can now control the relay. Clicking the “ON” button will activate the relay, while clicking the “OFF” button will deactivate it. The relay, in turn, will control the connected high-power device accordingly.


In this article, we learned how to control a relay using an Arduino web server. We explored the required components, the circuit diagram, and the step-by-step instructions to build the project. By creating a web interface, we can now remotely control high-power devices over the internet using an Arduino board. This opens up possibilities for home automation, remote monitoring, and more. So, go ahead, unleash your creativity, and start building your own Arduino web server control relay project!

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