Ultrasonic distance sensor (HC-SR04) in Arduino - Mini Project: Build & Apply

Ultrasonic distance sensor (HC-SR04)

📖 Scenario: You want to measure the distance to an object using an ultrasonic sensor (HC-SR04) connected to an Arduino board. This sensor sends out sound waves and listens for the echo to calculate how far the object is.

🎯 Goal: Build a simple Arduino program that reads the distance from the HC-SR04 sensor and prints the distance in centimeters to the Serial Monitor.

📋 What You'll Learn

Use pins 9 for triggerPin and 10 for echoPin.

Create a variable to store the duration of the echo pulse.

Calculate the distance in centimeters using the duration.

Print the distance to the Serial Monitor.

💡 Why This Matters

🌍 Real World

Ultrasonic sensors are used in robots, parking sensors, and obstacle detection to measure distances without touching objects.

💼 Career

Understanding how to read sensor data and process it is important for embedded systems and robotics jobs.

1

Set up sensor pins

Create two integer variables called triggerPin and echoPin and set them to 9 and 10 respectively.

Arduino

# Your code here

Hint

Use int to create the variables and assign the numbers 9 and 10.

2

Configure pins in setup

In the setup() function, set triggerPin as an output and echoPin as an input. Also, start the serial communication at 9600 baud using Serial.begin(9600);.

Arduino

int triggerPin = 9;
int echoPin = 10;

void setup() {
  // Your code here
}

Hint

Use pinMode() to set pin modes and Serial.begin(9600); to start serial communication.

3

Measure distance in loop

In the loop() function, send a 10 microsecond pulse to triggerPin, then read the pulse duration from echoPin using pulseIn(). Calculate the distance in centimeters by dividing the duration by 58 and store it in an integer variable called distance.

Arduino

int triggerPin = 9;
int echoPin = 10;

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

void loop() {
  // Send pulse and measure duration
  // Calculate distance
}

Hint

Send a short pulse on triggerPin, then use pulseIn() to measure the echo time. Divide by 58 to get centimeters.

4

Print the distance

Add a line in the loop() function to print the distance variable to the Serial Monitor using Serial.println(distance);.

Arduino

int triggerPin = 9;
int echoPin = 10;

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

void loop() {
  digitalWrite(triggerPin, LOW);
  delayMicroseconds(2);
  digitalWrite(triggerPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(triggerPin, LOW);

  long duration = pulseIn(echoPin, HIGH);
  int distance = duration / 58;
  // Print the distance
}

Hint

Use Serial.println(distance); to show the distance on the Serial Monitor.