Arduino - Web Server Multiple Pages

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About Arduino Uno R4 and Web Server

If you're not familiar with Arduino Uno R4 and Web Server (including pinout, how it works, and programming), you can learn about them through the following tutorials:

• How to get started with Arduino Uno R4
• Arduino - Web Server

How a web server on Arduino works

When a web browser sends an HTTP request to the Arduino board, the Arduino needs to be programmed to perform the following tasks:

• Create a web server that can listen for HTTP requests from the web browser.
• Read the first line of the HTTP request header when it receives an HTTP request.
• Route the requests based on the first line of the HTTP request to determine which web pages the Arduino should return.
• (Optionally) Analyze the HTTP request header to identify control commands sent by the user.
• (Optionally) Control the devices connected to the Arduino based on the received control commands.
• Send an HTTP response back to the web browser, which includes:
• An HTTP response header.
• The HTTP response body, which contains HTML content and (if applicable) sensor data or device state.

By performing these tasks, the Arduino can effectively handle HTTP requests and provide appropriate responses to the web browser, allowing for web-based control and interaction with the Arduino's connected devices.

The routing function is the most important task, and it will be explained in detail. Other parts are covered in the Arduino - Web Server tutorial. Once you understand the routing algorithm, we will proceed to see the complete code for a web server with multiple pages.

Arduino Web Server - Routing Algorithm

Before writing code for the routing function, you should create a list of web pages and corresponding HTTP methods that will be available on Arduino. In this tutorial, we will only support the GET method. However, you can easily extend it to include other HTTP methods if needed. Here is an example list:

• GET home page
• GET temperature page
• GET door page
• GET led page

After that, you need to create a list of the first-line HTTP request headers corresponding to the page list:

• GET home page:
• GET /
• GET /index.html
• GET temperature page
• GET /temperature.html
• GET door page
• GET /door
• GET led page
• GET /led.html

In summary, we have the following list:

GET / GET /index.html GET /temperature.html GET /door.html GET /led.html

The following code demonstrates how to implement the routing function for a web server on Arduino.


if (HTTP_req.indexOf("GET") == 0) { // check if request method is GET if (HTTP_req.indexOf("GET / ") > -1 || HTTP_req.indexOf("GET /index.html ") > -1) { Serial.println("home page"); // TO BE IMPLEMENT } else if (HTTP_req.indexOf("GET /temperature.html ") > -1) { Serial.println("temperature page"); // TO BE IMPLEMENT } else if (HTTP_req.indexOf("GET /door.html ") > -1) { Serial.println("door page"); // TO BE IMPLEMENT } else if (HTTP_req.indexOf("GET /led.html ") > -1) { Serial.println("led page"); // TO BE IMPLEMENT } else { // 404 Not Found Serial.println("404 Not Found"); // TO BE IMPLEMENT } } else { // 405 Method Not Allowed Serial.println("405 Method Not Allowed"); // TO BE IMPLEMENT }

Feel free to modify the code to add or remove pages as needed. Now, let's update the routing function to handle links with or without the .html extension.


if (HTTP_req.indexOf("GET") == 0) { // check if request method is GET if (HTTP_req.indexOf("GET / ") > -1 || HTTP_req.indexOf("GET /index ") > -1 || HTTP_req.indexOf("GET /index.html ") > -1) { Serial.println("home page"); // TO BE IMPLEMENT } else if (HTTP_req.indexOf("GET /temperature ") > -1 || HTTP_req.indexOf("GET /temperature.html ") > -1) { Serial.println("temperature page"); // TO BE IMPLEMENT } else if (HTTP_req.indexOf("GET /door ") > -1 || HTTP_req.indexOf("GET /door.html ") > -1) { Serial.println("door page"); // TO BE IMPLEMENT } else if (HTTP_req.indexOf("GET /led ") > -1 || HTTP_req.indexOf("GET /led.html ") > -1) { Serial.println("led page"); // TO BE IMPLEMENT } else { // 404 Not Found Serial.println("404 Not Found"); // TO BE IMPLEMENT } } else { // 405 Method Not Allowed Serial.println("405 Method Not Allowed"); // TO BE IMPLEMENT }

Arduino Code - Multiple-page Web server

Below is the complete Arduino code that creates a web server with multiple pages. To keep it simple, the HTML content for each page is very simple and embedded directly in the Arduino code. In the next part, we will learn how to separate the HTML contents for each page into separate files, making the code more organized and manageable.

Quick Steps

• If this is the first time you use Arduino Uno R4, see how to setup environment for Arduino Uno R4 on Arduino IDE.
• Copy the above code and open with Arduino IDE
• Change the wifi information (SSID and password) in the code to yours
• Click Upload button on Arduino IDE to upload code to Arduino
• Open the Serial Monitor
• Check out the result on Serial Monitor.

• You will see an IP address on the Serial Monitor, for example: 192.168.0.2
• Type the following list one-by-one on the address bar of a web browser on your smartphone or PC.

• Please note that you need to change the 192.168.0.2 to the IP address you got on Serial Monitor.
• You will see the following pages: home page, led page, door page, temperature page, and Not Found page
• You can also check the output on Serial Monitor

The previous code has very simple HTML content for each page. But if we want to make a fancy interface with lots of HTML, the code can get big and messy. To make it simpler, we will learn how to separate the HTML from the Arduino code. This lets us keep the HTML in separate files, making it easier to manage and work with.

Arduino Code - Complete multiple-page Web server

• Open the Arduino IDE.
• Create a new sketch and give it a name, for example, ArduinoWebServer.ino.
• Copy the provided code and paste it into that file.

• Change the WiFi information (SSID and password) in the code to yours
• Create the index.h file On Arduino IDE by:
• Either click on the button just below the serial monitor icon and choose New Tab, or use Ctrl+Shift+N keys.

• Give file's name index.h and click OK button

• Copy the below code and paste it to the index.h file.

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-web-server-multiple-pages */ const char *HTML_CONTENT_HOME = R""""( <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <link rel="icon" href="data:,"> <title>Home Page</title> </head> <body> <h1>Welcome to the Home Page</h1> <ul> <li><a href="/led">LED Page</a></li> <li><a href="/temperature">Temperature Page</a></li> <li><a href="/door">Door Page</a></li> </ul> </body> </html> )"""";
• Similarly, Create the temperature.h file On Arduino IDE with the following content.

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-web-server-multiple-pages */ const char *HTML_CONTENT_TEMPERATURE = R""""( <!DOCTYPE html> <html> <head> <title>Arduino - Web Temperature</title> <meta name="viewport" content="width=device-width, initial-scale=0.7, maximum-scale=0.7"> <meta charset="utf-8"> <link rel="icon" href="https://diyables.io/images/page/diyables.svg"> <style> body { font-family: "Georgia"; text-align: center; font-size: width/2pt;} h1 { font-weight: bold; font-size: width/2pt;} h2 { font-weight: bold; font-size: width/2pt;} button { font-weight: bold; font-size: width/2pt;} </style> <script> var cvs_width = 200, cvs_height = 450; function init() { var canvas = document.getElementById("cvs"); canvas.width = cvs_width; canvas.height = cvs_height + 50; var ctx = canvas.getContext("2d"); ctx.translate(cvs_width/2, cvs_height - 80); update_view(TEMPERATURE_MARKER); } function update_view(temp) { var canvas = document.getElementById("cvs"); var ctx = canvas.getContext("2d"); var radius = 70; var offset = 5; var width = 45; var height = 330; ctx.clearRect(-cvs_width/2, -350, cvs_width, cvs_height); ctx.strokeStyle="blue"; ctx.fillStyle="blue"; //5-step Degree var x = -width/2; ctx.lineWidth=2; for (var i = 0; i <= 100; i+=5) { var y = -(height - radius)*i/100 - radius - 5; ctx.beginPath(); ctx.lineTo(x, y); ctx.lineTo(x - 20, y); ctx.stroke(); } //20-step Degree ctx.lineWidth=5; for (var i = 0; i <= 100; i+=20) { var y = -(height - radius)*i/100 - radius - 5; ctx.beginPath(); ctx.lineTo(x, y); ctx.lineTo(x - 25, y); ctx.stroke(); ctx.font="20px Georgia"; ctx.textBaseline="middle"; ctx.textAlign="right"; ctx.fillText(i.toString(), x - 35, y); } // shape ctx.lineWidth=16; ctx.beginPath(); ctx.arc(0, 0, radius, 0, 2 * Math.PI); ctx.stroke(); ctx.beginPath(); ctx.rect(-width/2, -height, width, height); ctx.stroke(); ctx.beginPath(); ctx.arc(0, -height, width/2, 0, 2 * Math.PI); ctx.stroke(); ctx.fillStyle="#e6e6ff"; ctx.beginPath(); ctx.arc(0, 0, radius, 0, 2 * Math.PI); ctx.fill(); ctx.beginPath(); ctx.rect(-width/2, -height, width, height); ctx.fill(); ctx.beginPath(); ctx.arc(0, -height, width/2, 0, 2 * Math.PI); ctx.fill(); ctx.fillStyle="#ff1a1a"; ctx.beginPath(); ctx.arc(0, 0, radius - offset, 0, 2 * Math.PI); ctx.fill(); temp = Math.round(temp * 100) / 100; var y = (height - radius)*temp/100.0 + radius + 5; ctx.beginPath(); ctx.rect(-width/2 + offset, -y, width - 2*offset, y); ctx.fill(); ctx.fillStyle="red"; ctx.font="bold 34px Georgia"; ctx.textBaseline="middle"; ctx.textAlign="center"; ctx.fillText(temp.toString() + "°C", 0, 100); } window.onload = init; </script> </head> <body> <h1>Arduino - Web Temperature</h1> <canvas id="cvs"></canvas> </body> </html> )"""";
• Similarly, Create the door.h file On Arduino IDE with the following content.

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-web-server-multiple-pages */ const char *HTML_CONTENT_DOOR = R""""( <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <link rel="icon" href="data:,"> <title>Door Page</title> </head> <body> <h1>Door Page</h1> <p>Door State: <span style="color: red;">DOOR_STATE_MARKER</span></p> </body> </html> )"""";
• Similarly, Create the led.h file On Arduino IDE with the following content.

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-web-server-multiple-pages */ const char *HTML_CONTENT_LED = R""""( <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <link rel="icon" href="data:,"> <title>LED Page</title> </head> <body> <h1>LED Page</h1> <p>LED State: <span style="color: red;">LED_STATE_MARKER</span></p> </body> </html> )"""";
• Similarly, Create the error_404.h file On Arduino IDE with the following content.

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-web-server-multiple-pages */ const char *HTML_CONTENT_404 = R""""( <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <link rel="icon" href="data:,"> <title>404 - Page Not Found</title> <style> h1 {color: #ff4040;} </style> </head> <body> <h1>404</h1> <p>Oops! The page you are looking for could not be found on Arduino Web Server.</p> <p>Please check the URL or go back to the <a href="/">homepage</a>.</p> <p>Or check <a href="https://arduinogetstarted.com/tutorials/arduino-web-server-multiple-pages"> Arduino Web Server</a> tutorial.</p> </body> </html> )"""";
• Similarly, Create the error_405.h file On Arduino IDE with the following content.

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-web-server-multiple-pages */ const char *HTML_CONTENT_405 = R""""( <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <link rel="icon" href="data:,"> <title>405 - Method Not Allowed</title> <style> h1 {color: #ff4040;} </style> </head> <body> <h1>405 - Method Not Allowed</h1> <p>Oops! The requested method is not allowed for this resource.</p> <p>Please check your request or go back to the <a href="/">homepage</a>.</p> <p>Or check <a href="https://arduinogetstarted.com/tutorials/arduino-web-server-multiple-pages"> Arduino Web Server</a> tutorial.</p> </body> </html> )"""";
• Now you have multiple files on Arduino IDE like below:

• Click Upload button on Arduino IDE to upload code to Arduino
• Access the web pages of Arduino board via web browser one by one as before. You will see all web page as below:


※ NOTE THAT:

• If you make changes to the HTML content within the index.h file but don't modify anything in the ArduinoWebServer.ino file, the Arduino IDE won't refresh or update the HTML content when you compile and upload the code to the ESP32.
• To force the Arduino IDE to update the HTML content in this situation, you need to make a modification in the ArduinoWebServer.ino file. For example, you can add an empty line or insert a comment. This action triggers the IDE to recognize that there have been changes in the project, ensuring that your updated HTML content gets included in the upload.

The Best Arduino Starter Kit

• See the best Arduino kit for beginner

See Also

• Arduino - Web Server
• Arduino - Web Server Password
• Arduino - WebSocket
• Arduino - Web Plotter
• Arduino - Controls Servo Motor via Web
• Arduino - Controls Car via Web
• Arduino - LED Matrix via Web
• Arduino - Temperature via Web
• Arduino - Controls Door Lock via Web
• Arduino Uno R4 WiFi controls LED via Web
• Arduino Uno R4 WiFi controls Relay via Web