Height Measurement

🔌 Circuit Diagram

🔗 Wiring Connections

Component Pin	Arduino Pin	Purpose
VCC	5V	Powers the ultrasonic sensor
GND	GND	Provides the ground connection
TRIG	Digital Pin 9	Sends the ultrasonic pulse
ECHO	Digital Pin 10	Receives the reflected pulse

⚡ Circuit Overview

Mount the ultrasonic sensor 6 feet above the ground so it points straight down. The Arduino triggers the sensor through the TRIG pin, receives the echo on the ECHO pin, and calculates a person's height from the measured distance.

💡 Hardware Tips

• Mount the sensor securely so it does not move during measurements.
• Measure the mounting height accurately before running the project.
• Keep the sensor facing straight down for the best results.
• Make sure TRIG is connected to pin 9 and ECHO to pin 10.
• Ask the person to stand still directly below the sensor while measuring.

#define TRIG_PIN 9
#define ECHO_PIN 10

const float MOUNT_HEIGHT_CM = 195.88;  // 6 feet

long duration;
float distanceCm;
float heightCm;

void setup() {
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);

  Serial.begin(9600);
  Serial.println("Ultrasonic Height Measurement Tool");
}

void loop() {
  // Trigger pulse
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  // Read echo
  duration = pulseIn(ECHO_PIN, HIGH, 30000);

  if (duration == 0) {
    Serial.println("No object detected");
    delay(500);
    return;
  }

  distanceCm = (duration * 0.0343) / 2;
  heightCm = MOUNT_HEIGHT_CM - distanceCm;

  // Basic sanity check
  if (heightCm < 50 || heightCm > 210) {
    Serial.println("Out of human height range");
  } else {
    int feet = heightCm / 30.48;
    int inches = (heightCm - (feet * 30.48)) / 2.54;

    Serial.print("Height: ");
    Serial.print(heightCm, 1);
    Serial.print(" cm  (");
    Serial.print(feet);
    Serial.print(" ft ");
    Serial.print(inches);
    Serial.println(" in)");
  }

  delay(500);
}

🧠 Code Explained

Variables

The program defines the TRIG and ECHO pins connected to the ultrasonic sensor. The MOUNT_HEIGHT_CM variable stores the sensor height of 195.88 cm, which is used to calculate the person's height.

Other variables store the echo time, measured distance, and final height calculation. These values change as different people stand below the sensor.

setup()

The setup() function runs once when the Arduino starts. It sets the TRIG pin as an output, the ECHO pin as an input, and starts communication with the Serial Monitor.

loop()

The loop() function repeatedly sends an ultrasonic pulse and waits for the echo to return. The Arduino uses this information to measure the distance from the sensor to the top of a person's head.

The measured distance is subtracted from the sensor mounting height to find the person's height. The result is displayed in centimeters and converted into feet and inches.

Calculations / Helper Functions

The pulseIn() function measures the time taken for the ultrasonic echo to return. The program converts this time into distance using the speed of sound formula.

The height calculation uses the formula: Height = Mounting Height - Sensor Distance. A check is included to ignore measurements outside a normal human height range.

📚 Key Concepts

• Variables store sensor readings and calculated values.
• Functions organize the Arduino program into clear sections.
• Ultrasonic sensors measure distance using sound waves.
• Serial Monitor displays live height measurements.
• if statements check whether measurements are valid.
• Mathematical calculations convert distance into height.

🎉 Great Job!

Amazing work! You built a smart height measurement system using an Arduino Uno and an ultrasonic sensor. Your project can measure a person's height automatically using distance sensing and coding.

🧠 What You Learned

• How ultrasonic sensors measure distance using sound waves.
• How to connect and control a sensor using Arduino.
• How to calculate height from a measured distance.
• How to display live sensor data using the Serial Monitor.
• How robotics and automation use sensors to solve real-world problems.

🏆 Next Challenges

1. Easy: Add an LED indicator that turns on when someone is detected.
2. Medium: Add a display screen to show the height without using a computer.
3. Advanced: Create a smart height tracking system that stores measurements and connects to the internet.

📤 Submit Your Project

1. Record a short demonstration video showing your height measurement project working.
2. Upload the video to YouTube as Public or Unlisted.
3. Copy the YouTube video link.
4. Paste the link into the submission form.

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