Smart Home Automation

Smart Home Automation

Image: X-10 smart home adapter.jpg by phylevn via Wikimedia Commons, CC BY 2.0

How It Works

• A Bluetooth (HC-05) or Wi-Fi (ESP8266/ESP32) module receives on/off commands from a smartphone app, which the controller maps to relay channels driving each appliance.
• A DHT11 sensor reports temperature and humidity; a PIR sensor reports motion — both feed the controller for automated, sensor-triggered switching alongside manual control.
• Relays isolate the low-voltage control circuit from the mains-powered appliances, switching each one safely on command.
• For the Wi-Fi variant, an IoT platform (Blynk or a custom dashboard) adds remote access and scheduling from anywhere, not just over local Bluetooth range.

Components

Arduino Uno/Mega or ESP8266/ESP32 (for Wi-Fi/IoT variant)
Bluetooth module (HC-05) or built-in Wi-Fi
Relay module (4/8-channel, appliance-rated)
DHT11 temperature/humidity sensor
PIR motion sensor
Smartphone app (Blynk / custom Android app)
Appliance wiring + enclosure

Applications

• Residential lighting and appliance control
• Energy-saving automated switching based on occupancy/temperature
• Elderly or mobility-limited resident assistance
• Small office automation

Advantages

• Reduces energy waste from appliances left running unnecessarily
• Sensor-triggered automation works even without manual input
• Bluetooth variant needs no internet; Wi-Fi variant adds remote/anywhere access
• Modular relay design scales to as many appliances as needed

Sample Code — Bluetooth Command + Sensor-Triggered Relay Control

// Simplified home automation - Arduino
int relayLight = 6, relayFan = 7;
int pirPin = 2;
#include 
#define DHTPIN 4
DHT dht(DHTPIN, DHT11);

void setup() {
  Serial.begin(9600); // HC-05 on Serial
  pinMode(relayLight, OUTPUT);
  pinMode(relayFan, OUTPUT);
  pinMode(pirPin, INPUT);
  dht.begin();
}

void loop() {
  if (Serial.available()) {
    char cmd = Serial.read();
    if (cmd == 'L') digitalWrite(relayLight, !digitalRead(relayLight)); // toggle light
    if (cmd == 'F') digitalWrite(relayFan, !digitalRead(relayFan));     // toggle fan
  }

  if (digitalRead(pirPin) == HIGH) digitalWrite(relayLight, HIGH); // motion -> light on

  float temp = dht.readTemperature();
  if (temp > 30.0) digitalWrite(relayFan, HIGH); // auto fan on hot rooms
}

Related Research

• Learning IoT: Basic Experiments of Home Automation using ESP8266, Arduino and XBee — IEEE Xplore