Introduction
Finding an available parking space can be difficult in crowded areas such as shopping malls, offices, colleges, hospitals and residential buildings. A Smart Parking System can solve this problem by automatically detecting whether parking spaces are occupied or available.
In this project, we use an Arduino, ultrasonic sensors, an LCD display, and a servo motor to create a simple automated parking system.
The ultrasonic sensors detect vehicles entering or occupying parking spaces. The Arduino processes the sensor information and displays the parking status. A servo motor can be used as an automatic entrance barrier.
How Does an Arduino Smart Parking System Work?
The basic working process is:
Vehicle → Ultrasonic Sensor → Arduino → Parking Status → LCD Display
When a vehicle approaches a parking slot, the ultrasonic sensor measures the distance between the sensor and the vehicle.
If the measured distance is below a predefined value, the Arduino considers that parking slot occupied.
If no vehicle is detected, the slot is considered available.
For example:
- Slot 1 → Occupied
- Slot 2 → Available
- Slot 3 → Occupied
- Slot 4 → Available
The LCD can display the current status.
Block Diagram
┌─────────────────────┐
│ Vehicle │
└──────────┬──────────┘
│
▼
┌──────────────────┐
│ Ultrasonic │
│ Sensors │
└────────┬─────────┘
│
▼
┌──────────────────┐
│ Arduino │
│ UNO │
└───────┬──────────┘
│
┌───────────┴───────────┐
│ │
▼ ▼
┌────────────────┐ ┌────────────────┐
│ LCD Display │ │ Servo Motor │
│ Parking Status │ │ Gate Control │
└────────────────┘ └────────────────┘
Components Required
| Component | Quantity | Purpose |
|---|---|---|
| Arduino UNO | 1 | Main controller |
| HC-SR04 Ultrasonic Sensor | 2–4 | Detect vehicles |
| 16×2 LCD Display | 1 | Display parking status |
| Servo Motor | 1 | Automatic gate |
| Breadboard | 1 | Circuit assembly |
| Jumper Wires | As required | Connections |
| 5V Power Supply | 1 | Power source |
Circuit Diagram
Arduino UNO
┌───────────────┐
│ │
HC-SR04 #1 ────►│ D2 / D3 │
│ │
HC-SR04 #2 ────►│ D4 / D5 │
│ │
Servo Motor ───►│ D9 │
│ │
LCD I2C ───────►│ SDA / SCL │
│ │
│ 5V GND │
└─┬─────────┬───┘
│ │
▼ ▼
+5V GND
Arduino Code
#include <Servo.h>
#define TRIG1 2
#define ECHO1 3
#define TRIG2 4
#define ECHO2 5
#define SERVO_PIN 9
Servo gateServo;
long getDistance(int trigPin, int echoPin)
{
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
long duration = pulseIn(echoPin, HIGH);
long distance = duration * 0.034 / 2;
return distance;
}
void setup()
{
Serial.begin(9600);
pinMode(TRIG1, OUTPUT);
pinMode(ECHO1, INPUT);
pinMode(TRIG2, OUTPUT);
pinMode(ECHO2, INPUT);
gateServo.attach(SERVO_PIN);
gateServo.write(0);
}
void loop()
{
long distance1 = getDistance(TRIG1, ECHO1);
long distance2 = getDistance(TRIG2, ECHO2);
bool slot1Occupied = distance1 < 10;
bool slot2Occupied = distance2 < 10;
Serial.print("Slot 1: ");
if (slot1Occupied)
Serial.println("Occupied");
else
Serial.println("Available");
Serial.print("Slot 2: ");
if (slot2Occupied)
Serial.println("Occupied");
else
Serial.println("Available");
if (!slot1Occupied || !slot2Occupied)
{
gateServo.write(90);
delay(2000);
gateServo.write(0);
}
delay(1000);
}
Advantages
- Simple to build
- Low-cost components
- Easy to program
- Real-time parking detection
- Can be expanded to multiple parking spaces
- Suitable for educational projects
- Can be upgraded with IoT connectivity
Troubleshooting
Ultrasonic sensor always shows zero
Check:
- TRIG connection
- ECHO connection
- Sensor power
- Common ground
- Arduino pin configuration
Servo is not moving
Check:
- Servo signal pin
- Power supply
- Ground connection
- Correct servo library
Parking status changes randomly
Try:
- Increasing the detection distance
- Improving sensor positioning
- Avoiding interference between multiple ultrasonic sensors
- Taking multiple readings and averaging them
LCD does not display anything
Check:
- VCC
- GND
- SDA/SCL connections
- I2C address
- LCD contrast
Conclusion
The Arduino-Based Smart Parking System is a practical electronics project that demonstrates how sensors, microcontrollers and automation can work together to solve a real-world problem.
By combining Arduino UNO, ultrasonic sensors, an LCD display and a servo motor, you can build a working parking-management prototype.
The same concept can later be expanded using IoT, mobile applications, RFID, cameras and cloud services, making it a useful foundation for advanced smart-city and automation projects.
Want to build this project? Get the required electronics components from Electro Robo Store and start building your own Smart Parking System.
