🚧 Smart Automatic Gate

An Arduino-based automatic gate system that uses an ultrasonic sensor to detect approaching objects and controls a servo motor to open and close a gate autonomously.

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📖 Overview

The Smart Automatic Gate is a proximity-triggered gate controller built on an Arduino UNO. An HC-SR04 ultrasonic sensor continuously measures the distance to nearby objects. When something comes within 100 cm, the gate (driven by a servo motor) swings open automatically and stays open for 3 seconds before closing again — no button press or human interaction needed.

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✨ Features

• 📡 Contactless detection — HC-SR04 ultrasonic sensor measures distance without physical contact
• 🔁 Automatic open/close — gate opens on approach and closes once the path is clear
• ⏱️ Timed hold-open — stays open for 3 seconds to allow passage before auto-closing
• 🖥️ Serial monitoring — real-time distance and gate state logs via Serial Monitor (9600 baud)
• 🔒 State-aware logic — uses a boolean flag to prevent redundant servo commands

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🛠️ Hardware Components

Component	Quantity
Arduino UNO	1
HC-SR04 Ultrasonic Sensor	1
SG90 Servo Motor	1
Breadboard	1
Jumper Wires	As needed

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🔌 Pin Connections

Component	Pin	Arduino Pin
HC-SR04	VCC	5V
HC-SR04	GND	GND
HC-SR04	TRIG	Digital 7
HC-SR04	ECHO	Digital 6
Servo Motor	Signal	Digital 9
Servo Motor	VCC	5V
Servo Motor	GND	GND

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🔌 Circuit Diagram

Built and simulated in Tinkercad

Breadboard View:

Schematic View:

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🚀 Getting Started

Prerequisites

• Arduino IDE (1.8.x or 2.x)
• Servo.h library — included with the Arduino IDE by default

Installation

1. Clone the repository

git clone https://github.com/deep-chatterjee/Smart-Automatic-Gate.git
cd Smart-Automatic-Gate

2. Open the sketch

   • Open Smart_Automatic_Gate.ino in the Arduino IDE
   • Select your board: Arduino UNO
   • Select the correct COM port

3. Upload to your board

   • Click Upload
   • Open Serial Monitor (baud rate: 9600) to observe distance readings and gate state

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💻 How It Works

HC-SR04 sends ultrasonic pulse
          ↓
Arduino measures echo return time
          ↓
Calculates distance (cm) = duration × 0.034 / 2
          ↓
    Distance < 100 cm?
      ↙           ↘
    YES             NO
     ↓               ↓
Servo → 90°      Servo → 0°
(Gate Opens)    (Gate Closes)
    ↓
Wait 3 seconds
    ↓
Resume polling

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📁 Project Structure

Smart-Automatic-Gate/
├── Smart_Automatic_Gate.ino              # Arduino sketch
├── images/
│   ├── Smart_Automatic_Gate_Circuit.png      # Tinkercad breadboard view
│   └── Smart_Automatic_Gate_Schematic.png    # Tinkercad schematic view
└── README.md

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🧠 What I Learned

• Interfacing the HC-SR04 ultrasonic sensor using pulseIn() for accurate time-of-flight measurement
• Controlling a servo motor with the built-in Servo.h library
• Implementing state-based logic with boolean flags to avoid unnecessary actuator commands
• Debugging embedded systems in real time using Arduino Serial Monitor

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🔮 Future Improvements

• Add an IR or PIR sensor as a secondary detection method for improved reliability
• Introduce an LCD display to show distance and gate status locally
• Implement a password-protected override (keypad or RFID) for manual control
• Add a warning buzzer or LED indicator that activates before the gate moves
• Wireless control via Bluetooth module (HC-05) or Wi-Fi (ESP8266)

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👤 Author

Deep Chatterjee
GitHub

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📄 License

This project is licensed under the MIT License — see LICENSE for details.