Arduino Project
Speed Detection
Course Introduction
This Arduino project functions as a basic speed detection system using two infrared (IR) sensors and an LCD display.
When a vehicle passes the front sensor, the system starts a timer; it stops the timer once the vehicle triggers the back sensor.
Using the known distance between the sensors, the system calculates the vehicle’s speed and displays it in km/h on a 16x2 I2C LCD.
If the speed exceeds a set threshold (e.g., 60 km/h), a buzzer alerts for overspeeding. The LCD resets after each detection cycle, ready for the next vehicle.
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:
Passive Buzzer
＋: Connect to 4 on the Arduino.
－: Connect to breadboard’s negative power bus.
I2C LCD 1602
SDA: Connect to A4 on the Arduino.
SCL: Connect to A5 on the Arduino.
GND: Connect to breadboard’s negative power bus.
VCC: Connect to breadboard’s red power bus.
IR Obstacle Avoidance Sensor Module Front
OUT: Connect to 2 on the Arduino.
GND: Connect to breadboard’s negative power bus.
VCC: Connect to breadboard’s red power bus.
IR Obstacle Avoidance Sensor Module Back
OUT: Connect to 3 on the Arduino.
GND: Connect to breadboard’s negative power bus.
VCC: Connect to breadboard’s red power bus
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
#include
// Initialize LCD with I2C address 0x27, 16 columns and 2 rows
LiquidCrystal_I2C lcd(0x27, 16, 2); // Common I2C addresses: 0x27 or 0x3F
// Define pin numbers for IR sensors and buzzer
const int irFront = 2; // Front IR sensor connected to digital pin 2
const int irBack = 3; // Back IR sensor connected to digital pin 3
const int buzzer = 4; // Active buzzer connected to digital pin 4
unsigned long t1 = 0, t2 = 0; // Time markers for calculating speed
bool carDetected = false; // Flag to track if a car has been detected
float distance = 1.30; // Distance between IR sensors in meters (e.g. 1.30 meters)
void setup() {
pinMode(irFront, INPUT); // Set front IR sensor as input
pinMode(irBack, INPUT); // Set back IR sensor as input
pinMode(buzzer, OUTPUT); // Set buzzer pin as output
lcd.init(); // Initialize the LCD
lcd.backlight(); // Turn on LCD backlight
lcd.setCursor(0, 0);
lcd.print("No car detected"); // Display default message
}
void loop() {
// Wait for a car to pass the front sensor
if (!carDetected && digitalRead(irFront) == LOW) {
carDetected = true; // Mark that a car has been detected
t1 = millis(); // Record time when front sensor is triggered
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("searching...");
while (digitalRead(irBack) == HIGH); // Wait until back sensor is triggered
t2 = millis(); // Record time when back sensor is triggered
unsigned long deltaT = t2 - t1; // Calculate time difference in milliseconds
float timeSec = deltaT / 1000.0; // Convert time to seconds
float speed = (distance / timeSec) * 3.6; // Calculate speed in km/h
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("SPeed: ");
lcd.print((int)speed);
lcd.print("KM/Hr");
lcd.setCursor(0, 1);
if (speed <= 60.0) {
lcd.print("Normal Sreed"); // Display if speed is within limit
} else {
lcd.print("Over Speeding"); // Display warning for overspeed
digitalWrite(buzzer, HIGH); // Turn on buzzer
delay(1000); // Wait 1 second
digitalWrite(buzzer, LOW); // Turn off buzzer
}
delay(3000); // Display result for 3 seconds
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("No car detected"); // Reset to default message
carDetected = false; // Ready for next car
}
}