Arduino Project
Barrier Gate 1.0
Course Introduction
In this lesson, you’ll learn how to use an ultrasonic sensor module, a digital servo motor, and LEDs with the Arduino Board to build an intelligent barrier gate system.
When the barrier is closed, the red LED turns on. If the ultrasonic sensor module detects an approaching vehicle, the digital servo motor raises the barrier, the green LED turns on, and the vehicle is allowed to pass.
Note
If this is your first time working with an Arduino project, we recommend downloading and reviewing the basic materials first.
1.1 Install Arduino IDE(Important)
1.2 Introduction of Arduino IDE
Wiring
Common Connections:
Ultrasonic Sensor Module
Trig: Connect to 11 on the Arduino.
Echo: Connect to 10 on the Arduino.
GND: Connect to breadboard’s negative power bus.
VCC: Connect to breadboard’s red power bus.
LED
Connect the LEDs cathode to a 1kΩ resistor then to the negative power bus on the breadboard, and the LEDs anode to 3, 4 on the Arduino.
Digital Servo Motor
Connect to breadboard’s positive power bus.
Connect to breadboard’s negative power bus.
Connect to 2 on the Arduino.
Writing the Code
Note
You can copy this code into Arduino IDE.
To install the library, use the Arduino Library Manager and search for LiquidCrystal I2C and install it.
Don’t forget to select the board(Arduino UNO R4 WIFI) and the correct port before clicking the Upload button.
#include
const int trigPin = 11; // Trig pin of ultrasonic sensor
const int echoPin = 10; // Echo pin of ultrasonic sensor
const int redLed = 3; // Red LED pin
const int greenLed = 4; // Green LED pin
const int servoPin = 2; // Servo signal pin
Servo barrierServo; // Create servo object
bool previousCarDetected = false; // Record if a car was detected in last loop
void setup() {
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
pinMode(redLed, OUTPUT);
pinMode(greenLed, OUTPUT);
barrierServo.attach(servoPin); // Attach servo to pin
barrierServo.write(0); // Start with barrier down
Serial.begin(9600); // Start serial monitor
}
void loop() {
long duration, distance;
// Send ultrasonic pulse
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
// Read the time for echo to return
duration = pulseIn(echoPin, HIGH);
distance = duration * 0.034 / 2; // Convert time to distance (cm)
Serial.print("Distance: ");
Serial.println(distance);
// Check if car is within 15 cm
bool carDetected = (distance > 0 && distance < 15);
if (carDetected) {
// Car is detected: raise barrier and turn on green LED
digitalWrite(redLed, LOW);
digitalWrite(greenLed, HIGH);
barrierServo.write(90);
} else {
// If car just left: delay before lowering barrier
if (previousCarDetected) {
delay(1000); // Wait 1 second before lowering
}
// No car: lower barrier and turn on red LED
digitalWrite(redLed, HIGH);
digitalWrite(greenLed, LOW);
barrierServo.write(0);
}
previousCarDetected = carDetected; // Update last detection state
delay(300); // Small delay before next reading
}