🚦 Arduino Distance Indicator using HC-SR04
💡 The Idea
🧰 Building the Circuit
💻 Making the Arduino Understand Distance
😂 The One-Hour Build
🧠 What I Learned
🚀 What Could Be Improved
❤️ Final Thoughts
💙 Thanks for checking out my project

Published September 10, 2026 © GPL3+

Arduino Distance Indicator

An Arduino-based distance indicator that uses an HC-SR04 ultrasonic sensor and colorful LEDs to visualize object distance in real time.

BeginnerFull instructions provided1 hour30

Things used in this project

Hardware components

Male/Male Jumper Wires

Resistor 220 ohm

Ultrasonic Sensor - HC-SR04 (Generic)

Breadboard (generic)

Arduino UNO

USB-A to Mini-USB Cable

Software apps and online services

Arduino IDE

Story

🚦 Arduino Distance Indicator using HC-SR04

Sometimes the best projects start with a very simple thought:

“Let's just try something and see what happens.” 😂

That’s exactly how this project started.

I wanted to experiment with the HC-SR04 ultrasonic sensor and see if I could turn the distance it detects into something visual and fun. Instead of only displaying a distance value, I decided to use a row of colorful LEDs to create a simple distance indicator.

And honestly... I didn't expect to enjoy it this much. 😭

💡 The Idea

The basic idea was pretty simple:

Detect distance → process it with Arduino → show it through LEDs.

I used an Arduino UNO as the brain of the project and connected it to an HC-SR04 ultrasonic sensor.

The sensor detects how far an object is, and depending on the detected distance, different LEDs light up.

The LEDs are arranged like a little visual scale:

🔵 Blue → 🟢 Green → 🟡 Yellow → 🔴 Red

As the object gets closer, the LED indication changes accordingly.

So instead of having to constantly look at numbers, I can just look at the LEDs and get a quick visual idea of the distance.

🧰 Building the Circuit

For this project, I used:

🔌 Arduino UNO

🔌 Arduino UNO

📡 HC-SR04 Ultrasonic Sensor

📡 HC-SR04 Ultrasonic Sensor

💡 2 Blue LEDs

💡 2 Blue LEDs

💡 2 Green LEDs

💡 2 Green LEDs

💡 2 Yellow LEDs

💡 2 Yellow LEDs

💡 2 Red LEDs

💡 2 Red LEDs

⚡ Resistors

⚡ Resistors

🔗 Jumper wires

🔗 Jumper wires

🧱 Breadboard

🧱 Breadboard

💻 USB cable

💻 USB cable

I connected the LEDs through resistors and wired the ultrasonic sensor to the Arduino.

Then came the fun part...

Testing everything. 😭😂

💻 Making the Arduino Understand Distance

The HC-SR04 works by sending an ultrasonic pulse and measuring the time taken for the echo to return.

The Arduino uses that information to calculate the approximate distance of the object.

I then used different distance ranges to control the LEDs.

The basic logic is:

Object farther away🔵 Blue LEDs

↓

Object comes closer🟢 Green LEDs

↓

Object gets even closer🟡 Yellow LEDs

↓

Object is very close🔴 Red LEDs

Watching the LEDs change as I moved my hand closer and farther from the sensor was honestly the most satisfying part of the whole build. 😂🌈

😂 The One-Hour Build

One thing I really enjoyed about this project was how quickly it came together.

I didn't spend days designing some huge complicated system.

It was basically:

Idea 💡 → Components 🧰 → Wiring 🔌 → Code 💻 → Testing 🧪 → “WAIT... IT WORKS!” 😭🎉

Of course, there were moments of checking the wiring and making sure everything was connected properly, but that's also what made the experience fun.

It reminded me that even a small project can teach you a lot when you actually build it yourself.

🧠 What I Learned

Even though this is a relatively simple project, it gave me hands-on practice with several concepts:

How an ultrasonic sensor measures distance

How an ultrasonic sensor measures distance

Working with Arduino digital pins

Working with Arduino digital pins

Controlling multiple LEDs

Controlling multiple LEDs

Using resistors with LEDs

Using resistors with LEDs

Writing conditional logic

Writing conditional logic

Connecting hardware with software

Connecting hardware with software

Troubleshooting a physical circuit

Troubleshooting a physical circuit

Testing a project in real time

Testing a project in real time

Most importantly, I got to experience how something I wrote in code could directly control a physical circuit.

And that's honestly one of the things I enjoy most about working with Arduino and embedded systems. ⚡

🚀 What Could Be Improved?

This is only a starting point.

There are so many ways I could take this project further:

🔊 Add a buzzer for proximity warnings📺 Add an LCD or OLED to display the exact distance📱 Add Bluetooth connectivity🤖 Integrate it into a robot🚗 Turn it into a parking assistance system📊 Create a graphical distance monitor🔔 Make the buzzer change frequency based on distance

For now, though, I'm happy with this little experiment. ❤️

❤️ Final Thoughts

This project may be small, but it was a really fun hands-on experience.

I built it independently in around one hour, experimented with the sensor and LEDs, and got to see the whole system respond in real time.

It was a simple reminder that learning doesn't always have to start with a huge project.

Sometimes it can start with:

an Arduino + a sensor + some LEDs + a random idea + one free hour. 😂⚡

And that's exactly what happened here.

💙 Thanks for checking out my project!

If you found it interesting, I'd really appreciate your support, feedback, and encouragement! ✨

Feel free to like ❤️, comment 💬, and share your thoughts or ideas for improving the project.

Every bit of support motivates me to keep learning, building, and creating more! 🚀

More little experiments coming soon. 🌷

Result

The project successfully detected the distance of an object using the HC-SR04 ultrasonic sensor and displayed the result through the LEDs. As the object moved closer to the sensor, the LEDs changed accordingly from blue → green → yellow → red. The system responded in real time and worked as expected during testing. 🚦🌈

Seeing the LEDs respond to my hand movement was honestly the most satisfying part! 😂⚡ This small project gave me a fun hands-on experience with Arduino, sensors, and basic embedded system logic.

Code

Code

const int trigPin = 11;
const int echoPin = 12;
long duration;
int distanceCm, distanceInch;
void setup()
{

Serial.begin(9600); 
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
pinMode(3,OUTPUT);
pinMode(4,OUTPUT);
pinMode(5,OUTPUT);
pinMode(6,OUTPUT);
pinMode(7,OUTPUT);
pinMode(8,OUTPUT);
pinMode(9,OUTPUT);
pinMode(10,OUTPUT);



}
void loop() 
{
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
duration = pulseIn(echoPin, HIGH);
distanceCm= duration*0.034/2;
distanceInch = duration*0.0133/2;
Serial.println("Distance: ");
Serial.println(distanceCm);
delay(100);

if(distanceCm <6)
{
  digitalWrite(3,HIGH);
}
if(distanceCm >6)
{
  digitalWrite(3,LOW);
}

if(distanceCm <10)
{
  digitalWrite(4,HIGH);
}

if(distanceCm >10)
{
  digitalWrite(4,LOW);
}

if(distanceCm <15)
{
  digitalWrite(5,HIGH);
}

if(distanceCm >15)
{
  digitalWrite(5,LOW);
}


if(distanceCm <19)
{
  digitalWrite(6,HIGH);
}

if(distanceCm >19)
{
  digitalWrite(6,LOW);
}

if(distanceCm <23)
{
  digitalWrite(7,HIGH);
}

if(distanceCm >23)
{
  digitalWrite(7,LOW);
}


if(distanceCm <27)
{
  digitalWrite(8,HIGH);
}

if(distanceCm >27)
{
  digitalWrite(8,LOW);
}

if(distanceCm <30)
{
  digitalWrite(9,HIGH);
}

if(distanceCm >30)
{
  digitalWrite(9,LOW);
}

if(distanceCm <34)
{
  digitalWrite(10,HIGH);
}

if(distanceCm >34)
{
  digitalWrite(10,LOW);
}
}

Credits

Abrish Fatimaaah

4 projects • 1 follower

Arduino Distance Indicator