Chapter 12: Connecting to the Internet

The true potential of modern electronics is realized when they're connected. By interfacing Arduino with the Internet, you can remotely control devices, collect data from anywhere in the world, and build smart applications. This chapter offers a foray into the fascinating world of IoT using Arduino.

Basics of IoT (Internet of Things)

IoT, or the Internet of Things, refers to the vast network of physical devices connected to the Internet. These devices, equipped with sensors and actuators, can collect, send, and receive data, making informed decisions without human intervention.

In the context of Arduino, IoT implies connecting your board to the Internet, allowing it to send or receive data and interact with online services or other devices.

Using Ethernet Shields and WiFi Modules

1. Ethernet Shield (e.g., W5100):
Ethernet shields allow you to connect the Arduino to a wired network.

• Connection: Plug the shield onto the Arduino board.

• Code Snippet (Simple Web Server):

#include <SPI.h>
#include <Ethernet.h>

byte mac[] = {0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED};
IPAddress ip(192, 168, 1, 177);
EthernetServer server(80);

void setup() {
  Ethernet.begin(mac, ip);
  server.begin();
}

void loop() {
  EthernetClient client = server.available();
  if (client) {
    client.println("HTTP/1.1 200 OK");
    client.println("Content-Type: text/plain");
    client.println();
    client.println("Hello, world!");
    client.stop();
  }
}

2. WiFi Modules (e.g., ESP8266):
The ESP8266 is a popular module that offers WiFi capabilities.

• Connection: Varies based on the specific board and usage (as a standalone microcontroller or merely as a WiFi module for Arduino).

• Code Snippet (Simple Web Server using ESP8266):

#include <ESP8266WiFi.h>

const char* ssid = "your_SSID";
const char* password = "your_PASSWORD";
WiFiServer server(80);

void setup() {
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
  }
  server.begin();
}

void loop() {
  WiFiClient client = server.available();
  if (client) {
    client.println("HTTP/1.1 200 OK");
    client.println("Content-Type: text/plain");
    client.println();
    client.println("Hello from ESP8266!");
    client.stop();
  }
}

Basic Web Server and Client Applications

Web Server: As seen in the snippets above, a simple web server waits for incoming client requests. Upon a valid request, it sends back data (e.g., sensor readings, HTML pages).

Web Client: Arduino can also act as a client, making requests to external servers. This is useful for fetching online data or using web services.

Example (GET request using ESP8266):

#include <ESP8266WiFi.h>

const char* ssid = "your_SSID";
const char* password = "your_PASSWORD";
const char* host = "api.example.com";

void setup() {
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
  }
}

void loop() {
  WiFiClient client;
  if (client.connect(host, 80)) {
    client.println("GET /data HTTP/1.1");
    client.print("Host: ");
    client.println(host);
    client.println("Connection: close");
    client.println();
  }

  // Handle the response here

  delay(10000); // Wait for 10 seconds before the next request
}

Conclusion

IoT breathes life into the static world of electronics. Through Internet connectivity, devices can react to global data, be controlled remotely, and make autonomous decisions based on vast amounts of information. As you embark on your IoT journey with Arduino, a universe of possibilities in home automation, smart devices, and interconnected systems awaits exploration.