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Building an Ethernet Web Interface for Arduino

Graphic user interfaces have become an essential part of Arduino projects. This article aims to introduce the process of building a web interface by oneself and serving it through an Ethernet connection from an SD card. This will bring a new level of interaction to Arduino projects.

Essential Component: Arduino Ethernet Shield

Along with an Arduino, an Ethernet Shield is necessary to enable Ethernet communication. Following the official Arduino web tutorial to serve a simple web page allows users to control the ports of their Arduino. However, design matters too, so the appearance should also be considered.

Design with HTML and CSS

Websites are built using HTML and CSS. HTML is responsible for the structure, while CSS takes care of the design. Moving beyond simple HTML pages to add CSS increases the file size, potentially exceeding the Arduino's RAM capacity. To address this, using program memory through the pgmspace library is the first solution.

Serving a Webpage from the SD Card

While implementing a web interface may quickly deplete program memory, the Ethernet Shield's micro SD card slot provides a solution. This allows HTML and CSS files to be stored on the SD card and served over Ethernet. However, since only static files can be served, integrating dynamic data requires some thought.

Dynamic Data in the Arduino Web Interface

For a web interface built with Arduino, saving HTML and CSS on the SD card helps conserve Arduino's memory. However, it must be possible to add dynamic data before the page is transmitted over Ethernet. A simple marker is included in the HTML document to enable Arduino to insert the necessary data at the correct locations.

Processing the HTML File on Arduino

Arduino analyzes the HTML file, inserting dynamic data where needed. This process occurs after the web server has established a connection, ultimately providing the web page to the user.

Web Interface Design

The web interface is designed to be responsive, utilizing CSS3 technologies to implement various design elements. This ensures users have an efficient and aesthetically pleasing experience.