DIY Automatic gate using DC motor and Arduino

Hey guys, welcome back to the Techatronic. We have made a Project Automatic gate using DC motor. This is a simple programmable Project which use Arduino and ultrasonic sensor. the working of the project is very. simple whe any person comes in front of the sensor, which is placed at the gate front. so any person comes near the gate will open automatically. the gate mechanism uses the DC motor, which has high torque. so we are using gear motor. gears gives motor high torque. If you want to make this project please read full article i am going to share all the detail here and step by step instructions. you can attach this system with your other type of gate we have projects for the otheer type of gate. Automatic gate open & close. Now, lets start the making process.

Introduction

this is very simple and useful project which uses ultrasonic sesor , motor and Arduino by using C lagaueg which can make the program to operate this Project Automatic gate using DC motor. When you comes near the gate the sensor sense the object or person and gate will be close. this is very simple project. full video on how to make we have upload on the youtube. which we have given below.

An automatic gate system is commonly used in residential buildings, industries, parking areas, and restricted zones where controlled access is required. By using an Arduino microcontroller, the system can precisely control the movement of a DC motor that opens and closes the gate based on user commands or sensor inputs. The Arduino acts as the brain of the system, processing signals and controlling the motor through a motor driver circuit.

DC motors are preferred in this type of project because they are simple to control, cost-effective, and provide sufficient torque for gate movement. With the help of an H-bridge motor driver, the motor can rotate in both directions, allowing the gate to open and close smoothly. Additional components such as limit switches, IR sensors, or RF modules can be integrated to enhance safety and automation.

This project is an excellent example of how embedded systems can be applied to real-world problems. It helps beginners understand key concepts such as motor control, input-output interfacing, and Arduino programming. Moreover, the automatic gate system can be further upgraded with features like password control, RFID access, or mobile app operation, making it suitable for smart home and industrial applications.

Now, we are going to make this project. so , we will share the components list here.

Required Components for an Automatic gate using DC motor

You can buy the kit together here – BUY FULL KIT

Here we have given all the component required for this amazing project automatic Gate using DC motor. Now we need to assemble all the component. To assemble all the component we need a circuit diagram which can explain us how we can connect all the component together.

Circuit Diagram for an Automatic gate using DC motor

Circuit Diagram Explanation: Automatic Gate Using DC Motor & Arduino

This circuit shows an automatic gate system controlled by an Arduino Uno, a DC motor, an L298N motor driver, and an HC-SR04 ultrasonic sensor. The gate opens and closes automatically based on object detection.

1. Arduino Uno (Main Controller)

The Arduino Uno is the brain of the system.
It:

Reads distance data from the HC-SR04 ultrasonic sensor

Decides when to open or close the gate

Sends control signals to the L298N motor driver

Power Connections:

5V pin → Supplies power to the ultrasonic sensor

GND pin → Common ground for all components

2. Ultrasonic Sensor (HC-SR04)

The HC-SR04 sensor detects an object (vehicle/person) near the gate.

Pin Connections:

VCC → Arduino 5V

GND → Arduino GND

TRIG → Arduino digital pin (to send ultrasonic pulse)

ECHO → Arduino digital pin (to receive reflected signal)

Working:

The sensor sends ultrasonic waves

Measures the time taken for the echo to return

Arduino calculates distance

If distance is below a set value, the gate opens

3. L298N Motor Driver Module

The L298N is used to control the DC motor direction and speed, since Arduino cannot drive motors directly.

Connections to Arduino:

IN1 & IN2 → Control motor direction (open/close gate)

ENA → Enables motor (can be used with PWM for speed control)

GND → Connected to Arduino GND (common ground)

Power Connections:

12V input → Powered by the 9V battery

5V pin → Logic supply (depends on jumper configuration)

4. DC Motor (Gate Motor)

The DC motor represents the gate movement mechanism.

Connections:

Motor terminals → Connected to OUT1 & OUT2 of L298N

Working:

Motor rotates in one direction → Gate opens

Motor rotates in opposite direction → Gate closes

5. 9V Battery (Motor Power Supply)

Provides power to the L298N motor driver

Supplies sufficient current for the DC motor

Arduino and motor driver share a common ground

⚠️ Note: For real applications, a higher-current battery or power adapter is recommended instead of a 9V battery.

6. Breadboard (Power Distribution)

The breadboard is used to:

Distribute 5V and GND

Make neat and secure connections

Avoid soldering during testing

Overall Working of the Circuit

Ultrasonic sensor detects an object approaching the gate

Arduino calculates distance

If the object is within the preset range:

Arduino sends signals to L298N

DC motor rotates to open the gate

After a delay or when no object is detected:

Motor rotates in reverse

Gate closes automatically

After make conections wee need a code which cann help us to make our project Automatic gate using DC motor working.

Automatic gate using DC motor Code

// Ultrasonic sensor pins
#define trigPin 8
#define echoPin 9

// L298N motor pins
#define IN1 5
#define IN2 6
#define ENA 10

long duration;
int distance;

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

  pinMode(IN1, OUTPUT);
  pinMode(IN2, OUTPUT);
  pinMode(ENA, OUTPUT);

  stopMotor();

  Serial.begin(9600);
}

void loop() {
  distance = getDistance();

  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  if (distance > 0 && distance <= 20) {

    // Rotate Clockwise
    digitalWrite(IN1, HIGH);
    digitalWrite(IN2, LOW);
    analogWrite(ENA, 200);   // speed (0–255)
    delay(1000);
stopMotor();
    delay(1000);
    // Rotate Anti-Clockwise
    digitalWrite(IN1, LOW);
    digitalWrite(IN2, HIGH);
    analogWrite(ENA, 200);
    delay(1000);

    stopMotor();
    delay(500); // small delay before next detection
  }
  else {
    stopMotor();
  }

  delay(200);
}

// Function to stop motor
void stopMotor() {
  digitalWrite(IN1, LOW);
  digitalWrite(IN2, LOW);
  analogWrite(ENA, 0);
}

// Function to measure distance
int getDistance() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH, 30000); // timeout 30ms
  if (duration == 0) return -1;

  return duration * 0.034 / 2;
}

// Ultrasonic sensor pins
#define trigPin 8
#define echoPin 9

// L298N motor pins
#define IN1 5
#define IN2 6
#define ENA 10

long duration;
int distance;

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

  pinMode(IN1, OUTPUT);
  pinMode(IN2, OUTPUT);
  pinMode(ENA, OUTPUT);

  stopMotor();

  Serial.begin(9600);
}

void loop() {
  distance = getDistance();

  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  if (distance > 0 && distance <= 20) {

    // Rotate Clockwise
    digitalWrite(IN1, HIGH);
    digitalWrite(IN2, LOW);
    analogWrite(ENA, 200);   // speed (0–255)
    delay(1000);
stopMotor();
    delay(1000);
    // Rotate Anti-Clockwise
    digitalWrite(IN1, LOW);
    digitalWrite(IN2, HIGH);
    analogWrite(ENA, 200);
    delay(1000);

    stopMotor();
    delay(500); // small delay before next detection
  }
  else {
    stopMotor();
  }

  delay(200);
}

// Function to stop motor
void stopMotor() {
  digitalWrite(IN1, LOW);
  digitalWrite(IN2, LOW);
  analogWrite(ENA, 0);
}

// Function to measure distance
int getDistance() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH, 30000); // timeout 30ms
  if (duration == 0) return -1;

  return duration * 0.034 / 2;
}

1. Pin Definitions

// Ultrasonic sensor pins

#define trigPin 8

#define echoPin 9

trigPin → Sends ultrasonic pulses (TRIG pin of HC-SR04)

echoPin → Receives reflected pulse (ECHO pin)

Arduino pin 8 triggers the sensor, and pin 9 reads the echo.

// L298N motor pins

#define IN1 5

#define IN2 6

#define ENA 10

These pins control the DC motor through the L298N motor driver.

IN1 and IN2 → Control motor direction

ENA → Controls motor speed using PWM

🔹 2. Global Variables

long duration;

int distance;

duration → Stores time taken by ultrasonic wave to return

distance → Stores calculated distance in centimeters

🔹 3. setup() Function

void setup() {

This function runs only once when Arduino starts.

Pin Mode Configuration

pinMode(trigPin, OUTPUT);

pinMode(echoPin, INPUT);

TRIG → Output (send sound pulse)

ECHO → Input (receive pulse)

pinMode(IN1, OUTPUT);

pinMode(IN2, OUTPUT);

pinMode(ENA, OUTPUT);

Sets motor driver pins as outputs.

Stop Motor at Start

stopMotor();

Ensures the motor does not rotate when Arduino powers on

Prevents sudden movement

Serial Monitor

Serial.begin(9600);

Starts serial communication

Used to display distance values on Serial Monitor

🔹 4. loop() Function

void loop() {

This function runs continuously.

Measure Distance

distance = getDistance();

Calls the getDistance() function to calculate distance using ultrasonic sensor.

Print Distance

Serial.print(“Distance: “);

Serial.print(distance);

Serial.println(” cm”);

Displays the measured distance in centimeters.

🔹 5. Distance Condition Logic

if (distance > 0 && distance <= 20) {

Checks if an object is detected

Distance must be less than or equal to 20 cm

🔄 Motor Clockwise Rotation

digitalWrite(IN1, HIGH);

digitalWrite(IN2, LOW);

analogWrite(ENA, 200);

delay(2000);

Motor rotates clockwise

Speed ≈ 80% (200 out of 255)

Runs for 2 seconds

🔄 Motor Anti-Clockwise Rotation

digitalWrite(IN1, LOW);

digitalWrite(IN2, HIGH);

analogWrite(ENA, 200);

delay(2000);

Motor rotates anti-clockwise

Same speed

Runs for 2 seconds

🛑 Stop Motor

stopMotor();

delay(500);

Motor stops completely

Waits 0.5 seconds

Prevents sudden direction change

If No Object Detected

else {

  stopMotor();

}

If distance > 20 cm or invalid

Motor remains OFF

Small Loop Delay

delay(200);

Reduces sensor noise

Prevents rapid re-triggering

🔹 6. stopMotor() Function

void stopMotor() {

  digitalWrite(IN1, LOW);

  digitalWrite(IN2, LOW);

  analogWrite(ENA, 0);

}

What it does:

Stops motor direction

Sets motor speed to zero

Motor completely stops

🔹 7. getDistance() Function (Ultrasonic Logic)

Trigger Ultrasonic Pulse

digitalWrite(trigPin, LOW);

delayMicroseconds(2);

digitalWrite(trigPin, HIGH);

delayMicroseconds(10);

digitalWrite(trigPin, LOW);

Sends a 10µs ultrasonic pulse

Sensor emits sound waves

Measure Echo Time

duration = pulseIn(echoPin, HIGH, 30000);

Measures time taken for sound to return

Timeout after 30 ms (prevents freezing)

Handle No Echo

if (duration == 0) return -1;

If no object detected

Returns invalid distance

Calculate Distance

return duration * 0.034 / 2;

Speed of sound = 0.034 cm/µs

Divide by 2 (to-and-fro travel)

Result in centimeters

After completing the Circuit and Code. Now we need to upload the code into the Arduino.

Working of the project Automatic gate using DC motor

The working of this project is very simple there is an ultrasonic sensor which we have placed near the gate if someone comes in front of the gate the sensor will sense the person or object then it will send the command to the arduino. That there is something in front of the sensor the sensor continuously check the presence of any person or object. The ultrasonic sensor transmit the Ultrasonic waves to sense the object. the arduino react according to the signal. Arduino send command to the motor driver to rotate the motor anti clockwise for one second then stop for 1 second and again the motor rotate in clockwise direction for one second so this process make the kit open and close and study for one second. The duration of open and close gate can be differ as per your gear length. Here you can use any power supply from 9 volt to 12 volt directly to your l298 motor driver.