Arduino Ultrasonic Sensor with LEDs and Buzzer

This project uses an Arduino Uno, an HC-SR04 ultrasonic sensor, 2 LEDs, and a buzzer to create a simple distance alert system.

Components

• Arduino Uno
• HC-SR04 Ultrasonic Sensor
• 2 LEDs (Red and Green)
• Buzzer
• Jumper wires
• Breadboard (optional)

How it works

1. The ultrasonic sensor continuously measures distance.
2. LEDs light up based on the measured distance:
   • Green LED: Object is far
   • Red LED: Object is too close
3. Buzzer sounds when the object is within a critical distance.

Wiring

• HC-SR04
  • VCC → 5V
  • GND → GND
  • Trig → Arduino pin 9
  • Echo → Arduino pin 10
• Red LED → Arduino pin 2 (with resistor)
• Green LED → Arduino pin 3 (with resistor)
• Buzzer → Arduino pin 4

Installation

1. Connect the components as described above.
2. Upload the UltrasonicLEDsBuzzer.ino sketch to the Arduino.
3. Observe LEDs and buzzer reacting to distance changes.

Code Example

#include <Arduino.h>

const int trigPin = 9;
const int echoPin = 10;
const int redLED = 2;
const int greenLED = 3;
const int buzzer = 4;
long duration;
int distance;

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(redLED, OUTPUT);
  pinMode(greenLED, OUTPUT);
  pinMode(buzzer, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  // Ultrasonic distance measurement
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  distance = duration * 0.034 / 2;
  Serial.println(distance);

  // LED and buzzer control
  if (distance < 10) {
    digitalWrite(redLED, HIGH);
    digitalWrite(greenLED, LOW);
    digitalWrite(buzzer, HIGH);
  } else {
    digitalWrite(redLED, LOW);
    digitalWrite(greenLED, HIGH);
    digitalWrite(buzzer, LOW);
  }
  delay(200);
}