Situatie

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) / 2

The 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_SSD1306 and Adafruit_GFX libraries drive the OLED.
• Display refreshes every 0.5 seconds for updated readings.

Install these via Arduino IDE → Sketch → Include Library → Manage Libraries:

• Adafruit SSD1306
• Adafruit 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

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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.

Solutie

Tip solutie

Permanent