Building a Distance-Measuring LED Indicator Using Arduino and Ultrasonic Sensor 🔥

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Summary

Learn to create a distance-measuring LED indicator using an Arduino and an HC-SR04 ultrasonic sensor. This project guides you through setting up the sensor to control LEDs based on object proximity, offering a hands-on introduction to Arduino programming and electronics. Includes full code, hardware setup, and further reading recommendations for advancing your skills.

Arduino Project: Ultrasonic Sensor with LED Indicators

Welcome to this in-depth guide on building a simple yet effective Arduino project that uses an ultrasonic sensor to measure distance and control a series of LEDs. This project is ideal for beginners looking to expand their knowledge of Arduino, sensors, and basic electronics.

I had made this video in january 2022

Project Overview

In this project, we will utilize the HC-SR04 ultrasonic sensor to measure distances and light up LEDs based on the proximity of an object. This can be the foundation for a variety of applications, such as proximity alarms, automated lighting systems, or even robotics. The LEDs will provide visual feedback, lighting up in different patterns depending on how close an object is to the sensor.

Components Required

Arduino board (e.g., Arduino Uno)
HC-SR04 Ultrasonic Sensor
Three LEDs (any color)
Three 220Ω Resistors
Jumper wires
Breadboard

Understanding the Hardware Setup

The hardware setup is straightforward. The ultrasonic sensor has four pins:

VCC: Connects to 5V on the Arduino.
GND: Connects to the ground (GND) on the Arduino.
Trig: Connects to pin 8 on the Arduino.
Echo: Connects to pin 11 on the Arduino.

Each LED is connected to a digital pin on the Arduino (pins 3, 5, and 6) through a 220Ω resistor to limit the current and prevent damage to the LEDs.

Explaining the Code

Let’s dive into the code that brings this project to life. The code is structured in two main sections: the setup() function and the loop() function. The setup() function runs once when the Arduino is powered on or reset, and it initializes the pins. The loop() function contains the main logic and runs repeatedly.

Setup Function

In the setup() function, we start by initializing the serial communication at a baud rate of 9600, which allows us to see the distance readings on the serial monitor. We then define the pin modes for the ultrasonic sensor and the LEDs.

void setup() {
  Serial.begin(9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
  pinMode(led3, OUTPUT);
}

Loop Function

The loop() function contains the core logic of the project. The ultrasonic sensor works by sending out a sound pulse through the trigger pin and measuring the time it takes for the echo to return. This time is then used to calculate the distance to an object.

void loop() {
   long duration, distance;
   digitalWrite(trigPin, HIGH);
   delayMicroseconds(10);
   digitalWrite(trigPin, LOW);
   duration = pulseIn(echoPin, HIGH);
   distance = (duration / 2) / 29.1;
   Serial.print("Distance: ");
   Serial.print(distance);
   Serial.println(" cm");
   delay(10);

Based on the calculated distance, different LEDs are lit up or made to blink. Here’s how the LEDs behave for various distance ranges:

Distance < 5 cm: All LEDs are off, indicating that the object is very close.
5 cm < Distance < 10 cm: The first LED lights up.
10 cm < Distance < 15 cm: The second LED lights up.
15 cm < Distance < 20 cm: The third LED lights up.
20 cm < Distance < 30 cm: All three LEDs light up simultaneously.
Distance > 30 cm: The LEDs blink in sequence, creating a visual effect that indicates the object is far away.

Here’s the code that handles this logic:

// Code for LED blinking based on distance
if (distance < 5) {
  digitalWrite(led1, LOW);
  digitalWrite(led2, LOW);
  digitalWrite(led3, LOW);
} else if (distance > 5 && distance < 10) {
  digitalWrite(led1, HIGH);
  digitalWrite(led2, LOW);
  digitalWrite(led3, LOW);
} else if (distance > 10 && distance < 15) {
  digitalWrite(led1, LOW);
  digitalWrite(led2, HIGH);
  digitalWrite(led3, LOW);
} else if (distance > 15 && distance < 20) {
  digitalWrite(led1, LOW);
  digitalWrite(led2, LOW);
  digitalWrite(led3, HIGH);
} else if (distance > 20 && distance < 30) {
  digitalWrite(led1, HIGH);
  digitalWrite(led2, HIGH);
  digitalWrite(led3, HIGH);
} else if (distance > 30) {
  digitalWrite(led1, HIGH);
  digitalWrite(led2, LOW);
  digitalWrite(led3, LOW);
  delay(50);
  digitalWrite(led1, LOW);
  digitalWrite(led2, HIGH);
  digitalWrite(led3, LOW);
  delay(50);
  digitalWrite(led1, LOW);
  digitalWrite(led2, LOW);
  digitalWrite(led3, HIGH);
  delay(50);
}

Full Code for the Project

Below is the complete code for this project. You can copy and paste this directly into your Arduino IDE:


int trigPin = 8;
int echoPin = 11;
int led1 = 3;
int led2 = 5;
int led3 = 6;

void setup() {
  Serial.begin(9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
  pinMode(led3, OUTPUT);
}

void loop() {
   long duration, distance;
   digitalWrite(trigPin, HIGH);
   delayMicroseconds(10);
   digitalWrite(trigPin, LOW);
   duration = pulseIn(echoPin, HIGH);
   distance = (duration / 2) / 29.1;
   Serial.print("Distance: ");
   Serial.print(distance);
   Serial.println(" cm");
   delay(10);

   if (distance < 5) {
     digitalWrite(led1, LOW);
     digitalWrite(led2, LOW);
     digitalWrite(led3, LOW);
   } else if (distance > 5 && distance < 10) {
     digitalWrite(led1, HIGH);
     digitalWrite(led2, LOW);
     digitalWrite(led3, LOW);
   } else if (distance > 10 && distance < 15) {
     digitalWrite(led1, LOW);
     digitalWrite(led2, HIGH);
     digitalWrite(led3, LOW);
   } else if (distance > 15 && distance < 20) {
     digitalWrite(led1, LOW);
     digitalWrite(led2, LOW);
     digitalWrite(led3, HIGH);
   } else if (distance > 20 && distance < 30) {
     digitalWrite(led1, HIGH);
     digitalWrite(led2, HIGH);
     digitalWrite(led3, HIGH);
   } else if (distance > 30) {
     digitalWrite(led1, HIGH);
     digitalWrite(led2, LOW);
     digitalWrite(led3, LOW);
     delay(50);
     digitalWrite(led1, LOW);
     digitalWrite(led2, HIGH);
     digitalWrite(led3, LOW);
     delay(50);
     digitalWrite(led1, LOW);
     digitalWrite(led2, LOW);
     digitalWrite(led3, HIGH);
     delay(50);
   }
}

Conclusion and Next Steps

This project is a great way to get hands-on experience with Arduino and basic electronics. You’ve learned how to use an ultrasonic sensor to measure distances and control LEDs based on the proximity of objects. As a next step, consider expanding this project by adding more LEDs, integrating a buzzer for auditory feedback, or displaying the distance on an LCD screen.