Arduino Distance Sensor with OLED Display
This project uses an HC-SR04 Ultrasonic Distance Sensor and a 0.96” I2C OLED display to measure and display the distance to an object in real-time.
It’s an excellent beginner-to-intermediate Arduino project that teaches sensor interfacing, I2C communication, and real-time data display.
In this guide, you’ll learn how to:
- Connect and use the HC-SR04 Ultrasonic Sensor
- Display the measured distance on an OLED screen
- Format readings for easy readability
Components Required
| Component | Quantity | Description |
|---|---|---|
| Arduino Uno / Nano / Mega | 1 | Main controller |
| HC-SR04 Ultrasonic Sensor | 1 | Measures distance via sound waves |
| 0.96” OLED Display (SSD1306) | 1 | I2C display for output |
| Breadboard | 1 | For wiring |
| Jumper wires | 6–8 | Male-to-male connections |
| USB cable | 1 | For programming and power |
The HC-SR04 measures distance by sending out an ultrasonic pulse and timing how long it takes to bounce back.
The Arduino calculates the distance based on the time delay and the known speed of sound.
Distance Formula:
Distance (cm) = (Time in microseconds × 0.034) / 2The division by 2 accounts for the round trip of the sound wave (out and back).
Pin Connections
| Component | Arduino Pin | Notes |
|---|---|---|
| HC-SR04 VCC | 5V | Power supply |
| HC-SR04 GND | GND | Common ground |
| HC-SR04 TRIG | D9 | Trigger pin |
| HC-SR04 ECHO | D10 | Echo pin |
| OLED VCC | 5V | Power |
| OLED GND | GND | Ground |
| OLED SDA | A4 | I2C Data |
| OLED SCL | A5 | I2C Clock |
Note: On Arduino Mega, use SDA = 20 and SCL = 21 instead.
Arduino Code Example
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#define TRIG_PIN 9
#define ECHO_PIN 10
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);
void setup() {
Serial.begin(9600);
pinMode(TRIG_PIN, OUTPUT);
pinMode(ECHO_PIN, INPUT);
// Initialize OLED
if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
Serial.println("OLED not found!");
while (true);
}
display.clearDisplay();
display.setTextSize(1);
display.setTextColor(SSD1306_WHITE);
display.setCursor(0, 0);
display.println("Distance Sensor");
display.display();
delay(1500);
}
void loop() {
long duration;
float distance;
// Send trigger pulse
digitalWrite(TRIG_PIN, LOW);
delayMicroseconds(2);
digitalWrite(TRIG_PIN, HIGH);
delayMicroseconds(10);
digitalWrite(TRIG_PIN, LOW);
// Measure echo time
duration = pulseIn(ECHO_PIN, HIGH);
distance = (duration * 0.034) / 2;
// Print to Serial Monitor
Serial.print("Distance: ");
Serial.print(distance);
Serial.println(" cm");
// Display on OLED
display.clearDisplay();
display.setTextSize(1);
display.setCursor(0, 0);
display.println("Distance Sensor");
display.setTextSize(2);
display.setCursor(0, 30);
display.print(distance, 1);
display.println(" cm");
display.display();
delay(500);
}
Explanation: The Arduino sends a pulse from the HC-SR04 and measures the time it takes to return.
It then converts this time into distance and displays it on the OLED screen.
Code Breakdown
pulseIn()measures the length of time the echo pin is HIGH.- Distance is calculated using the speed of sound (0.034 cm/μs).
Adafruit_SSD1306andAdafruit_GFXlibraries drive the OLED.- Display refreshes every 0.5 seconds for updated readings.
Install these via Arduino IDE → Sketch → Include Library → Manage Libraries:
Adafruit SSD1306Adafruit GFX
Search for “Adafruit SSD1306” and “Adafruit GFX” and click Install.
Troubleshooting
| Issue | Cause | Solution |
|---|---|---|
| OLED blank | Wrong I2C address | Try changing 0x3C to 0x3D |
| Distance always 0 | Echo pin not connected | Check TRIG and ECHO wiring |
| Unstable readings | Object too close or far | HC-SR04 range: 2–400 cm |
| Serial Monitor empty | Wrong baud rate | Ensure 9600 baud in Serial Monitor |
Optional Upgrades
- Add a buzzer that activates when an object is too close.
- Display a bar graph or animation on the OLED.
- Send readings to the cloud using ESP8266 / ESP32.
- Log readings to an SD card.
Applications
- Parking assist system
- Object detection robot
- Smart trash bin (auto open lid)
- Liquid level detector.