Home Automation System using NodeMCU

Difficulty Level: Intermediate

This project will guide you through building a basic home automation system using the NodeMCU (ESP8266). You will be able to control lights, fans, or other appliances remotely over Wi-Fi through a simple web interface.

Required Components

• 1 x NodeMCU (ESP8266) Development Board
• 1 x 4-channel Relay Module
• 4 x AC Appliances (like lights or fans)
• Jumper wires
• USB cable to connect NodeMCU to your computer
• Optional: 5V power supply for relays

Wiring the NodeMCU

Connect the relay module to the NodeMCU as follows:

• IN1 -> GPIO 5 (D1)
• IN2 -> GPIO 4 (D2)
• IN3 -> GPIO 14 (D5)
• IN4 -> GPIO 12 (D6)
• VCC -> 5V (External 5V supply or VIN pin of NodeMCU)
• GND -> GND

Each relay channel controls one appliance, and the relays are connected in parallel with the appliances.

Code Explanation

The following code will enable control of the relays via a web interface hosted on the NodeMCU.

Key Functions

• digitalWrite(): Sets the GPIO pins high or low to turn the relay on or off.
• WiFi.begin(): Connects the NodeMCU to your Wi-Fi network.
• server.on(): Defines the web server routes for controlling devices.

Arduino Code

Here’s the Arduino code for controlling home appliances through relays using NodeMCU:

#include 
#include 

const char* ssid = "YOUR_SSID";
const char* password = "YOUR_PASSWORD";

ESP8266WebServer server(80);

// Relay pins
const int relay1 = 5; // D1
const int relay2 = 4; // D2
const int relay3 = 14; // D5
const int relay4 = 12; // D6

void setup() {
  Serial.begin(115200);

  // Set relay pins as outputs
  pinMode(relay1, OUTPUT);
  pinMode(relay2, OUTPUT);
  pinMode(relay3, OUTPUT);
  pinMode(relay4, OUTPUT);

  // Start with all relays off
  digitalWrite(relay1, HIGH);
  digitalWrite(relay2, HIGH);
  digitalWrite(relay3, HIGH);
  digitalWrite(relay4, HIGH);

  // Connect to Wi-Fi
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi...");
  }
  Serial.println("Connected to WiFi");

  // Define routes for controlling appliances
  server.on("/", handleRoot);
  server.on("/relay1/on", []() {
    digitalWrite(relay1, LOW); // Relay ON
    server.send(200, "text/plain", "Relay 1 ON");
  });
  server.on("/relay1/off", []() {
    digitalWrite(relay1, HIGH); // Relay OFF
    server.send(200, "text/plain", "Relay 1 OFF");
  });

  // Similar routes for other relays
  server.on("/relay2/on", []() {
    digitalWrite(relay2, LOW);
    server.send(200, "text/plain", "Relay 2 ON");
  });
  server.on("/relay2/off", []() {
    digitalWrite(relay2, HIGH);
    server.send(200, "text/plain", "Relay 2 OFF");
  });

  server.on("/relay3/on", []() {
    digitalWrite(relay3, LOW);
    server.send(200, "text/plain", "Relay 3 ON");
  });
  server.on("/relay3/off", []() {
    digitalWrite(relay3, HIGH);
    server.send(200, "text/plain", "Relay 3 OFF");
  });

  server.on("/relay4/on", []() {
    digitalWrite(relay4, LOW);
    server.send(200, "text/plain", "Relay 4 ON");
  });
  server.on("/relay4/off", []() {
    digitalWrite(relay4, HIGH);
    server.send(200, "text/plain", "Relay 4 OFF");
  });

  server.begin(); // Start the server
}

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

void handleRoot() {
  String html = "
Home Automation Control
"
                "Turn ON Relay 1
"
                "Turn OFF Relay 1
"
                "Turn ON Relay 2
"
                "Turn OFF Relay 2
"
                "Turn ON Relay 3
"
                "Turn OFF Relay 3
"
                "Turn ON Relay 4
"
                "Turn OFF Relay 4
";
  server.send(200, "text/html", html);
}
            

Upload and Test

1. Connect your NodeMCU to your computer using the USB cable.
2. Open the Arduino IDE and copy the code above into the editor.
3. Replace YOUR_SSID and YOUR_PASSWORD with your Wi-Fi credentials.
4. Select your NodeMCU board and the correct port in the IDE.
5. Click the upload button to send the code to the NodeMCU.
6. Open the Serial Monitor to find the IP address of the NodeMCU.
7. Enter the IP address into a web browser to access the control interface.

Conclusion

In this project, we built a home automation system using NodeMCU, a relay module, and a web interface. This setup allows you to control multiple appliances remotely over Wi-Fi. You can expand this project further by integrating sensors or adding more devices to the system.