🏠 Home Automation Hub

Take control of your room with an ESP32 web server and relay module.

📋 Overview

Relays are electrically operated switches. They allow a low-voltage microcontroller (like the 3.3V ESP32) to safely switch high-voltage loads (like 120V/240V lamps or fans).

What you'll learn: Relay module logic (active low vs active high), web server routing, and controlling multiple digital outputs from a web interface.

Estimated time: 1.5-2 hours. Difficulty: ⭐⭐⭐ Intermediate.

🧩 Components Needed

Component	Specification	Qty	Notes
ESP32 Development Board	WiFi enabled	1
4-Channel Relay Module	5V Coil, 3.3V input tolerant	1	Opto-isolated preferred
Jumper Wires	Female-to-Male	~6
Appliance/Lamp	For testing	1	USE CAUTION WITH AC VOLTAGE

📖 Step-by-Step Tutorial

Wire the Relays

Connect Relay VCC to ESP32 5V (VIN), GND to GND. Connect IN1, IN2, IN3, IN4 to GPIOs 13, 12, 14, 27.

Setup the Web Server

We will use ESPAsyncWebServer to serve an HTML page with toggle buttons for each relay.

Upload Code

Enter your WiFi credentials and upload. Find the IP address in the Serial Monitor.

Test Switching

Click the buttons on the web interface. You should hear the relays "click" as they switch states.

AC Wiring (Advanced)

Warning: High Voltage. Splice the hot wire of an appliance cord and connect it to the Common (COM) and Normally Open (NO) terminals of a relay.

💡

Many relay modules are "Active Low", meaning pulling the pin to LOW turns the relay ON. Keep this in mind when writing your logic.

💻 Code / Configuration

home_hub.ino

INO

// Home Automation Hub - Volt X
#include <WiFi.h>
#include <AsyncTCP.h>
#include <ESPAsyncWebServer.h>

const char* ssid = "YOUR_WIFI_SSID";
const char* password = "YOUR_WIFI_PASSWORD";

const int relay1 = 13;
bool relay1State = false;

AsyncWebServer server(80);

void setup() {
  Serial.begin(115200);
  pinMode(relay1, OUTPUT);
  digitalWrite(relay1, HIGH); // Active low relay off

  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) { delay(1000); }
  
  Serial.println(WiFi.localIP());

  server.on("/", HTTP_GET, [](AsyncWebServerRequest *request){
    String html = "<html><body><h1>Volt X Hub</h1>";

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