🌐 ESP32 Wi-Fi Basics

The ESP32 comes with built-in Wi-Fi, making it one of the most powerful and popular microcontrollers for IoT applications. In this tutorial, you’ll learn how Wi-Fi works on ESP32 and how to connect it to a router using the Arduino IDE.

Connecting to Wi-Fi is something we do daily—just enter a Wi-Fi SSID and password, and your device is online. In the Internet of Things (IoT), Wi-Fi is a key player, and ESP32 makes it easy to build connected devices thanks to its built-in Wi-Fi module.

Smart homes, weather stations, and cloud-connected sensors are just a few examples of where Wi-Fi plays a vital role.

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🔄 ESP32 Wi-Fi Modes

ESP32 supports two main Wi-Fi modes:

Mode	Description
STA (Station)	ESP32 connects to your home router like a phone or laptop. This is the most common mode.
AP (Access Point)	ESP32 creates its own Wi-Fi hotspot. Other devices can connect to it directly, but it won’t have internet access unless bridged.

🔸 Use STA mode when you want ESP32 to connect to the internet via your router.

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🔧 Hardware Setup

You don’t need any external Wi-Fi module. Just use an ESP32 development board and a USB cable to connect it to your computer.

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🧾 Wi-Fi Functions in Arduino

Here are the most useful Wi-Fi functions from the ESP32 WiFi library:

🔌 WiFi.begin(ssid, password)

Connect to a Wi-Fi network.

WiFi.begin("yourSSID", "yourPASSWORD");

🔌 WiFi.disconnect()

Disconnect from the current Wi-Fi network.

📶 WiFi.status()

Check connection status. Returns:

• WL_CONNECTED – Connected to Wi-Fi
• WL_DISCONNECTED – Not connected
• WL_IDLE_STATUS – Idle
• WL_NO_SSID_AVAIL – Network not found

🌐 WiFi.localIP()

Returns the local IP address assigned by the router.

🔎 WiFi.macAddress()

Returns the MAC address of the ESP32.

📡 WiFi.scanNetworks()

Scans for available Wi-Fi networks. Returns the number of networks found.

📋 WiFi.SSID(index)

Returns the SSID of the network at the given index from scan results.

📈 WiFi.RSSI(index)

Returns the signal strength (RSSI) of the scanned network at the given index.

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🧪 Example Code: Connect to Router

#include <WiFi.h>

const char* ssid = "yourSSID";
const char* password = "yourPASSWORD";

void setup() {
  Serial.begin(115200);
  WiFi.begin(ssid, password);
  
  Serial.print("Connecting to WiFi");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("\nWiFi Connected!");
  Serial.print("IP Address: ");
  Serial.println(WiFi.localIP());
}

void loop() {
  // Do something with the connection
}

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🛰️ Bonus: Scan Nearby Networks

void setup() {
  Serial.begin(115200);
  WiFi.mode(WIFI_STA);
  WiFi.disconnect();
  delay(100);

  Serial.println("Scanning...");

  int networks = WiFi.scanNetworks();
  for (int i = 0; i < networks; i++) {
    Serial.print(i + 1);
    Serial.print(": ");
    Serial.print(WiFi.SSID(i));
    Serial.print(" (");
    Serial.print(WiFi.RSSI(i));
    Serial.println(" dBm)");
  }
}

void loop() {}