In modern smart homes, security automation has become an essential feature. In this project, we will create an IoT Smart Door Lock using an ESP32, a 12V Solenoid Lock, and the Blynk IoT App. This system allows users to lock and unlock their door remotely from anywhere in the world using their smartphone.

The ESP32 communicates with the Blynk IoT cloud via Wi-Fi, providing real-time control and status monitoring. The solenoid lock is controlled through a 2-Channel Relay Module, making the entire setup safe, reliable, and fully automated. An I2C LCD Display is added to show system status, such as “Door Locked”, “Door Unlocked”, or “Connecting to Wi-Fi…”

This project is a perfect example of a Smart Home Automation System, ideal for beginners and advanced makers who want to explore IoT Security Systems, ESP32 projects, and remote access control.

Objectives of the IoT Smart Door Lock Project:

• To build an IoT-based door lock system using ESP32
• To control a 12V Solenoid Lock via Blynk App
• To display real-time lock status on an I2C LCD module
• To create a secure and user-friendly Smart Home Door Access System
• To understand Wi-Fi Based automation using Blynk IoT Cloud

Components Required for the IoT Smart Door Lock Project :

• ESP32 Development Board
• 2-Channel Relay Module
• 12V DC Solenoid Lock
• 12V Power Adapter
• Breadboard & Jumper Wires
• I2C 16×2 LCD Display
• Blynk IoT Mobile App (Android/iOS)
• Wi-Fi Network

Working Principle IoT Smart Door Lock:

This IoT Door Lock System works using Wi-Fi communication, relay control, and a solenoid lock mechanism.

1. ESP32 as the Brain

The ESP32 connects to your Wi-Fi router and communicates with the Blynk IoT Cloud. Whenever the user presses the LOCK/UNLOCK button on the Blynk app, a command is instantly sent to the ESP32.

2. Relay Module for Switching

The ESP32 sends a signal to the 2-Channel Relay Module, which acts as an electronic switch.

• When the relay turns ON → Solenoid Lock activates → Door Unlocks
• When the relay turns OFF → Lock becomes inactive → Door Locks

3. Solenoid Lock Operation

A solenoid lock needs 12V DC to operate. The relay safely switches the 12V supply without exposing the ESP32 to high current.

4. I2C LCD Display

The 16×2 I2C LCD shows real-time messages like:

• “System Ready”
• “Wi-Fi Connected”
• “Door Locked”
• “Door Unlocked”

This makes the system more user-friendly and professional.

5. Blynk IoT App Control

Using the Blynk app, the user can control the door lock from:

• Home
• Office
• Another city
• Even another country

This provides remote security management, which is the core purpose of modern IoT systems.

Circuit Diagram of IoT Smart Door Lock with ESP32:

ESP32 → Relay Module

• Relay IN1 → ESP32 GPIO 14
• Relay VCC → 5V
• Relay GND → GND

Relay → Solenoid Lock

• COM → 12V Adapter +
• NO → Solenoid +
• Solenoid – → Adapter –

I2C LCD → ESP32

• SDA → GPIO 21
• SCL → GPIO 22
• VCC → 5V
• GND → GND

Working Video of IoT Door Lock System:

Features of the ESP32 IoT Door Lock System:

• Remote Control via Blynk IoT App
• Wi-Fi Based Smart Security System
• Fast and Reliable Solenoid Lock Operation
• Onboard LCD Status Display
• Real-time Communication with IoT Cloud
• Perfect for Smart Home Automation Projects
• Highly scalable — add password, RFID, keypad, fingerprint, etc.

Applications IoT Smart Door Lock Project:

• Smart Home Door Lock System
• Office Entry Access Automation
• Hostel Room Smart Lock
• IoT Security Projects for Students
• Automation for Door Cabinets & Lockers
• Remote Access Smart Gate Lock

Advantages of IoT Smart Door Lock Project:

• Can be controlled from anywhere in the world
• Safe and reliable switching of 12V Lock
• Very low power consumption
• Cloud-connected smart security
• Easy expansion (RFID, Keypad, Face ID, etc.)

Conclusion:

The IoT Smart Door Lock using ESP32 and Blynk is an innovative and practical Smart Home Automation project. It demonstrates how IoT technology can enhance safety, convenience, and remote access capabilities. Using simple hardware like an ESP32, relay module, and solenoid lock, you can build a fully functional cloud-connected security system that works from any location.

This project is perfect for beginners learning ESP32 Wi-Fi control, students working on IoT projects, or makers developing smart home security systems.