Ultrasonic Distance Measurement Using Arduino

Difficulty Level: Beginner

In this project, we will measure the distance of an object using an HC-SR04 ultrasonic sensor connected to an Arduino. The measured distance will be displayed on the serial monitor and an optional LCD display.

Components Required

• 1 x Arduino (any model)
• 1 x HC-SR04 Ultrasonic Sensor
• 1 x 16x2 LCD Display (optional)
• Jumper Wires
• Breadboard

Wiring Diagram

Connect the HC-SR04 sensor to the Arduino as follows:

• HC-SR04 Ultrasonic Sensor:
• VCC to 5V on Arduino
• GND to GND on Arduino
• Trig to digital pin 9 on Arduino
• Echo to digital pin 10 on Arduino
• LCD Display (optional):
• SCL to A5 (SCL on Arduino)
• SDA to A4 (SDA on Arduino)
• VCC to 5V on Arduino
• GND to GND on Arduino

Code Explanation

The HC-SR04 sensor sends out ultrasonic pulses and listens for their echo. The time it takes for the echo to return is used to calculate the distance to an object. The Arduino will send out the trigger signal to the sensor, and the sensor will return the echo signal. The time taken for the echo to be received is converted into distance using the formula:

Distance = (Time * Speed of Sound) / 2

In this project, we will display the calculated distance in centimeters on the serial monitor.

Arduino Code

Here is the Arduino code for measuring distance with the HC-SR04 sensor:

const int trigPin = 9;
const int echoPin = 10;

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

void loop() {
  long duration, distance;

  // Clear the trigPin by setting it LOW
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  // Set the trigPin HIGH for 10 microseconds
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Read the echoPin and get the duration
  duration = pulseIn(echoPin, HIGH);

  // Calculate distance (speed of sound is 343 meters per second)
  distance = (duration * 0.034) / 2;

  // Display the distance on the Serial Monitor
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  // Wait before the next measurement
  delay(500);
}
            

Upload and Test

1. Connect your Arduino to the computer and upload the code.
2. Open the Serial Monitor to view the distance readings.
3. Point the sensor at an object and observe the changing distance values.

Optional: Display on LCD

If you want to display the distance on an LCD, you can use the LiquidCrystal_I2C library. The following additional code will allow you to display the distance on a 16x2 I2C LCD:

#include 
#include 

LiquidCrystal_I2C lcd(0x27, 16, 2);  // Define the LCD

void setup() {
  Serial.begin(9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  lcd.begin();
  lcd.backlight();
}

void loop() {
  long duration, distance;

  // Clear the trigPin by setting it LOW
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  // Set the trigPin HIGH for 10 microseconds
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Read the echoPin and get the duration
  duration = pulseIn(echoPin, HIGH);

  // Calculate distance
  distance = (duration * 0.034) / 2;

  // Display the distance on the Serial Monitor
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  // Display the distance on the LCD
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Distance:");
  lcd.setCursor(0, 1);
  lcd.print(distance);
  lcd.print(" cm");

  // Wait before the next measurement
  delay(500);
}
            

Conclusion

Using the HC-SR04 sensor, you can measure distances with accuracy and display the data either on the serial monitor or an optional LCD display. This project introduces the basics of ultrasonic distance measurement and can be further expanded for more complex applications like obstacle detection in robotics.