Arduino Distance Measurement Using Ultrasonic Sensor (HC-SR04) and LCD

 This project measures the distance of an object using the HC-SR04 ultrasonic sensor and displays the distance in centimeters on a 16×2 LCD. It works on the principle of ultrasonic sound wave reflection.

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🔧 Components Required

• Arduino UNO

• Ultrasonic Sensor HC-SR04

• 16×2 LCD

• 10kΩ Potentiometer (for LCD contrast)

• Breadboard

• Jumper wires

• USB cable

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⚙️ Working Principle

1. The Trigger pin sends an ultrasonic pulse.

2. The pulse hits an object and reflects back.

3. The Echo pin receives the reflected signal.

4. Arduino calculates distance using time delay.

5. Distance is displayed on the LCD.

📐 Distance Formula:

Distance (cm) = (Time × Speed of Sound) / 2
Speed of sound = 0.034 cm/µs

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🔌 Circuit Connections

HC-SR04 → Arduino

HC-SR04 Pin	Arduino Pin
VCC	5V
Trig	D9
Echo	D10
GND	GND

LCD → Arduino

LCD Pin	Arduino Pin
RS	D7
E	D6
D4	D5
D5	D4
D6	D3
D7	D2
VSS	GND
VDD	5V
V0	Potentiometer
RW	GND

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💻 Arduino Code

#include <LiquidCrystal.h>

LiquidCrystal lcd(7, 6, 5, 4, 3, 2);

const int trigPin = 9;
const int echoPin = 10;

long duration;
int distance;

void setup() {
  lcd.begin(16, 2);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  lcd.print("Distance Meter");
  delay(2000);
  lcd.clear();
}

void loop() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

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

  duration = pulseIn(echoPin, HIGH);
  distance = duration * 0.034 / 2;

  lcd.setCursor(0, 0);
  lcd.print("Distance:");
  lcd.setCursor(0, 1);
  lcd.print(distance);
  lcd.print(" cm   ");

  delay(500);
}

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📊 Output

• LCD displays real-time distance in centimeters

• Measurement range: 2 cm to 400 cm

• Accuracy: ±3 mm