WiFi & Networking on ESP32

WiFi on the ESP32

The ESP32 has a fully integrated WiFi stack. The WiFi.h library (included with the ESP32 Arduino core) exposes everything you need to connect, scan, and serve data.

Connecting to a WiFi Network (Station Mode)

Station mode means the ESP32 connects to an existing WiFi router ߀” just like a phone or laptop.

#include <WiFi.h>

const char* ssid     = "YourNetworkName";
const char* password = "YourPassword";

void setup() {
  Serial.begin(115200);
  WiFi.begin(ssid, password);

  Serial.print("Connecting");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println();
  Serial.print("Connected! IP address: ");
  Serial.println(WiFi.localIP());
}

void loop() { }

WiFi Status Codes

Constant	Value	Meaning
WL_CONNECTED	3	Connected to an AP
WL_DISCONNECTED	6	Not connected
WL_CONNECT_FAILED	4	Wrong password
WL_NO_SSID_AVAIL	1	SSID not found

Making an HTTP GET Request

Use the HTTPClient library to call REST APIs or fetch web pages:

#include <WiFi.h>
#include <HTTPClient.h>

void loop() {
  if (WiFi.status() == WL_CONNECTED) {
    HTTPClient http;
    http.begin("http://worldtimeapi.org/api/ip");
    int httpCode = http.GET();

    if (httpCode == 200) {
      String payload = http.getString();
      Serial.println(payload);
    }
    http.end();
  }
  delay(10000);
}

Hosting a Simple Web Server

Access Point + Web Server mode lets the ESP32 create its own WiFi network and serve pages:

#include <WiFi.h>
#include <WebServer.h>

WebServer server(80);

void handleRoot() {
  server.send(200, "text/html",
    "<h1>ESP32 Web Server</h1><p>GPIO 2: ON</p>");
}

void setup() {
  WiFi.begin("YourSSID", "YourPassword");
  while (WiFi.status() != WL_CONNECTED) delay(500);

  server.on("/", handleRoot);
  server.begin();
  Serial.println("Server started at: " + WiFi.localIP().toString());
}

void loop() {
  server.handleClient();
}

Scanning for Networks

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

Access Point (AP) Mode

The ESP32 can create its own WiFi hotspot:

WiFi.softAP("ESP32-Hotspot", "password123");
Serial.println(WiFi.softAPIP());  // Usually 192.168.4.1

Using HTTPS

For HTTPS you need the WiFiClientSecure library:

#include <WiFiClientSecure.h>
WiFiClientSecure client;
client.setInsecure();   // Skip certificate validation (not for production)

Tips for Reliable WiFi

• Always check WiFi.status() == WL_CONNECTED before making requests
• Use WiFi.setAutoReconnect(true) to reconnect automatically after drops
• Avoid delay() inside loop() when running a web server ߀” use millis() for timing
• Use WiFi.disconnect(true) and WiFi.begin() again to force a reconnect