Arduino Project

Arduino Object Width Measurement V1

Kit purchase

Looking for parts? Check out our all-in-one kits below — packed with components, beginner-friendly guides, and tons of fun.

2.webp__PID:7d088a16-8752-49fb-8b1f-f9bba7297987

Name	Includes Arduino board	PURCHASE LINK
Elite Explorer Kit	Arduino Uno R4 WiFi	BUY
3 in 1 Ultimate Starter Kit	Arduino Uno R4 Minima	BUY

Course Introduction

This Arduino project builds a basic object width measurement system using two Ultrasonic Sensor Modules and an OLED display.

The two sensors measure the distance from each side of an object to calculate its width.

The OLED shows the scanning process and displays the measured width in real time.

Note

If this is your first time working with an Arduino project, we recommend downloading and reviewing the basic materials first.

1.1 Install Arduino IDE(Important)
1.2 Introduction of Arduino IDE

Required Components

In this project, we need the following components:

SN	COMPONENT INTRODUCTION	QUANTITY	PURCHASE LINK
1	Arduino UNO R4 Minima/Arduino UNO R4 WIFI	1	BUY
2	USB Type-C cable	1	×
3	Breadboard	1	BUY
4	Wires	Several	BUY
5	OLED Display Module	1	BUY
6	Ultrasonic Sensor Module	2	BUY

Wiring

width_scan_bb.png__PID:ede195f1-0214-4ff1-bf54-d5d9a7764339

Common Connections:

Ultrasonic Sensor Module Left
Trig: Connect to 2 on the Arduino.
Echo: Connect to 3 on the Arduino.
GND: Connect to breadboard’s negative power bus.
VCC: Connect to breadboard’s red power bus.

Ultrasonic Sensor Module Right
Trig: Connect to 4 on the Arduino.
Echo: Connect to 5 on the Arduino.
GND: Connect to breadboard’s negative power bus.
VCC: Connect to breadboard’s red power bus.

OLED Display Module
SDA: Connect to SDA on the Arduino.
SCK: Connect to SCL on the Arduino.
GND: Connect to breadboard’s negative power bus.
VCC: Connect to breadboard’s red power bus.

Writing the Code

Note
You can copy this code into Arduino IDE.
To install the library, use the Arduino Library Manager and search for Adafruit_GFX and Adafruit SSD1306 and FluxGarage_RoboEyes and install it
Don’t forget to select the board(Arduino UNO R4 Minima/WIFI) and the correct port before clicking the Upload button.

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// =====================================================
// OLED
// =====================================================
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
#define OLED_ADDRESS 0x3C

Adafruit_SSD1306 display(
  SCREEN_WIDTH,
  SCREEN_HEIGHT,
  &Wire,
  OLED_RESET
);

// =====================================================
// Ultrasonic sensors
// =====================================================
#define LEFT_TRIG  2
#define LEFT_ECHO  3

#define RIGHT_TRIG 4
#define RIGHT_ECHO 5

// =====================================================
// Calibration
// =====================================================

// Distance between the front faces of two HC-SR04 sensors
const float SENSOR_GAP_CM = 10.0;

// Minimum width to recognize an object
const float MIN_OBJECT_WIDTH = 0.5;

// Maximum valid single-side distance
const float MAX_SIDE_DISTANCE = 10.0;

// =====================================================
// System state
// =====================================================
enum ScanState {
  READY,
  SCANNING,
  RESULT
};

ScanState state = READY;

float objectWidth = 0;
float leftDistance = 0;
float rightDistance = 0;

unsigned long resultTimer = 0;
unsigned long animationTimer = 0;

int readyAnimation = 0;

bool objectWasPresent = false;

// =====================================================
// Setup
// =====================================================
void setup() {

  Serial.begin(9600);

  pinMode(LEFT_TRIG, OUTPUT);
  pinMode(LEFT_ECHO, INPUT);

  pinMode(RIGHT_TRIG, OUTPUT);
  pinMode(RIGHT_ECHO, INPUT);

  digitalWrite(LEFT_TRIG, LOW);
  digitalWrite(RIGHT_TRIG, LOW);

  // Start I2C on Arduino UNO R4 WiFi
  Wire.begin();

  // Initialize OLED
  if (!display.begin(
        SSD1306_SWITCHCAPVCC,
        OLED_ADDRESS
      )) {

    Serial.println("OLED not found!");

    while (true);
  }

  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);

  showStartup();

  delay(1500);

  drawReadyScreen();
}

// =====================================================
// Main loop
// =====================================================
void loop() {

  switch (state) {

    case READY:
      readyMode();
      break;

    case SCANNING:
      scanObject();
      break;

    case RESULT:
      resultMode();
      break;
  }
}

// =====================================================
// Ready mode
// =====================================================
void readyMode() {

  // Ready animation
  if (millis() - animationTimer >= 250) {

    animationTimer = millis();

    readyAnimation++;

    if (readyAnimation > 3) {
      readyAnimation = 0;
    }

    drawReadyScreen();
  }

  // Read left sensor
  float left = readDistance(
    LEFT_TRIG,
    LEFT_ECHO
  );

  delay(35);

  // Read right sensor
  float right = readDistance(
    RIGHT_TRIG,
    RIGHT_ECHO
  );

  // Calculate estimated width
  float width =
    SENSOR_GAP_CM -
    left -
    right;

  bool objectDetected =
    left > 0 &&
    right > 0 &&
    left < MAX_SIDE_DISTANCE &&
    right < MAX_SIDE_DISTANCE &&
    width > MIN_OBJECT_WIDTH &&
    width < SENSOR_GAP_CM;

  // Detect a newly inserted object
  if (
    objectDetected &&
    !objectWasPresent
  ) {

    objectWasPresent = true;

    delay(200);

    state = SCANNING;
  }

  if (!objectDetected) {
    objectWasPresent = false;
  }
}

// =====================================================
// Scan object
// =====================================================
void scanObject() {

  const int SAMPLE_COUNT = 12;

  float leftTotal = 0;
  float rightTotal = 0;

  int validSamples = 0;

  for (
    int i = 0;
    i < SAMPLE_COUNT;
    i++
  ) {

    // Scanning animation
    drawScanningScreen(
      i,
      SAMPLE_COUNT
    );

    // Left sensor
    float left = readDistance(
      LEFT_TRIG,
      LEFT_ECHO
    );

    // Prevent ultrasonic interference
    delay(40);

    // Right sensor
    float right = readDistance(
      RIGHT_TRIG,
      RIGHT_ECHO
    );

    if (
      left > 0 &&
      right > 0 &&
      left < SENSOR_GAP_CM &&
      right < SENSOR_GAP_CM
    ) {

      leftTotal += left;
      rightTotal += right;

      validSamples++;
    }

    delay(70);
  }

  // ===================================================
  // Valid measurement
  // ===================================================
  if (validSamples >= 5) {

    leftDistance =
      leftTotal / validSamples;

    rightDistance =
      rightTotal / validSamples;

    objectWidth =
      SENSOR_GAP_CM -
      leftDistance -
      rightDistance;

    // Prevent invalid values
    objectWidth =
      constrain(
        objectWidth,
        0.0,
        SENSOR_GAP_CM
      );

    Serial.println("-------------------");

    Serial.print("Left: ");
    Serial.print(leftDistance, 1);
    Serial.println(" cm");

    Serial.print("Right: ");
    Serial.print(rightDistance, 1);
    Serial.println(" cm");

    Serial.print("Width: ");
    Serial.print(objectWidth, 1);
    Serial.println(" cm");

    drawResultScreen();
  }

  else {

    drawErrorScreen();
  }

  resultTimer = millis();

  state = RESULT;
}

// =====================================================
// Result mode
// =====================================================
void resultMode() {

  // Keep result on screen for at least 4 seconds
  if (
    millis() - resultTimer >=
    4000
  ) {

    float left = readDistance(
      LEFT_TRIG,
      LEFT_ECHO
    );

    delay(40);

    float right = readDistance(
      RIGHT_TRIG,
      RIGHT_ECHO
    );

    float width =
      SENSOR_GAP_CM -
      left -
      right;

    // Return to READY after object is removed
    if (
      left <= 0 ||
      right <= 0 ||
      width < MIN_OBJECT_WIDTH
    ) {

      objectWasPresent = false;

      state = READY;

      drawReadyScreen();
    }
  }
}

// =====================================================
// HC-SR04 distance measurement
// =====================================================
float readDistance(
  int trigPin,
  int echoPin
) {

  digitalWrite(trigPin, LOW);
  delayMicroseconds(3);

  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);

  digitalWrite(trigPin, LOW);

  unsigned long duration =
    pulseIn(
      echoPin,
      HIGH,
      25000
    );

  if (duration == 0) {
    return -1;
  }

  float distance =
    duration * 0.0343 / 2.0;

  return distance;
}

// =====================================================
// Startup screen
// =====================================================
void showStartup() {

  display.clearDisplay();

  display.setTextSize(1);

  display.setCursor(28, 10);
  display.println("OBJECT WIDTH");

  display.setCursor(40, 23);
  display.println("SCANNER");

  // Scanner frame
  display.drawRoundRect(
    14,
    40,
    100,
    10,
    3,
    SSD1306_WHITE
  );

  display.fillRect(
    18,
    43,
    60,
    4,
    SSD1306_WHITE
  );

  display.display();
}

// =====================================================
// Ready screen
// =====================================================
void drawReadyScreen() {

  display.clearDisplay();

  display.setTextSize(1);

  display.setCursor(27, 3);
  display.println("WIDTH SCANNER");

  display.drawLine(
    8,
    13,
    120,
    13,
    SSD1306_WHITE
  );

  // Center sensor/radar icon
  display.drawCircle(
    64,
    31,
    3,
    SSD1306_WHITE
  );

  display.fillCircle(
    64,
    31,
    1,
    SSD1306_WHITE
  );

  // Animated scanning waves
  if (readyAnimation >= 1) {

    display.drawCircle(
      64,
      31,
      7,
      SSD1306_WHITE
    );
  }

  if (readyAnimation >= 2) {

    display.drawCircle(
      64,
      31,
      11,
      SSD1306_WHITE
    );
  }

  if (readyAnimation >= 3) {

    display.drawCircle(
      64,
      31,
      15,
      SSD1306_WHITE
    );
  }

  // Cover top half to create radar-wave effect
  display.fillRect(
    45,
    15,
    38,
    16,
    SSD1306_BLACK
  );

  display.setCursor(27, 53);
  display.println("READY TO SCAN");

  display.display();
}

// =====================================================
// Scanning screen
// =====================================================
void drawScanningScreen(
  int step,
  int total
) {

  display.clearDisplay();

  display.setTextSize(1);

  display.setCursor(21, 3);
  display.println("SCANNING OBJECT");

  // Scanner frame
  display.drawRoundRect(
    7,
    16,
    114,
    30,
    5,
    SSD1306_WHITE
  );

  int progress =
    map(
      step + 1,
      0,
      total,
      0,
      100
    );

  int barWidth =
    map(
      progress,
      0,
      100,
      0,
      104
    );

  // Scanning vertical lines
  for (
    int x = 12;
    x < 12 + barWidth;
    x += 4
  ) {

    display.drawLine(
      x,
      20,
      x,
      41,
      SSD1306_WHITE
    );
  }

  // Moving scan line
  int scannerX =
    12 + barWidth;

  scannerX =
    constrain(
      scannerX,
      12,
      115
    );

  display.drawLine(
    scannerX,
    18,
    scannerX,
    43,
    SSD1306_WHITE
  );

  // Progress
  display.setCursor(28, 53);

  display.print("SCANNING ");

  display.print(progress);

  display.print("%");

  display.display();
}

// =====================================================
// Measurement result
// =====================================================
void drawResultScreen() {

  display.clearDisplay();

  display.setTextSize(1);

  display.setCursor(10, 2);
  display.println(
    "MEASUREMENT COMPLETE"
  );

  // Main box
  display.drawRoundRect(
    7,
    15,
    114,
    39,
    5,
    SSD1306_WHITE
  );

  display.setCursor(48, 19);
  display.println("WIDTH");

  // Large width number
  display.setTextSize(2);

  display.setCursor(28, 30);

  display.print(
    objectWidth,
    1
  );

  display.setTextSize(1);

  display.setCursor(82, 36);
  display.print("cm");

  // Measurement line
  display.drawLine(
    27,
    48,
    100,
    48,
    SSD1306_WHITE
  );

  display.drawLine(
    27,
    45,
    27,
    51,
    SSD1306_WHITE
  );

  display.drawLine(
    100,
    45,
    100,
    51,
    SSD1306_WHITE
  );

  display.setCursor(24, 57);
  display.println("WIDTH DETECTED");

  display.display();
}

// =====================================================
// Error screen
// =====================================================
void drawErrorScreen() {

  display.clearDisplay();

  display.setTextSize(1);

  display.setCursor(34, 14);
  display.println("SCAN ERROR");

  display.drawLine(
    35,
    27,
    93,
    27,
    SSD1306_WHITE
  );

  display.setCursor(18, 39);
  display.println("REPOSITION OBJECT");

  display.display();
}

Recover password

Create my account

Arduino Project

Arduino Object Width Measurement V1

Kit purchase

Course Introduction

Required Components

Wiring

Common Connections:

Writing the Code

Arduino Project

Arduino Object Width Measurement V1

Kit purchase

Course Introduction

Required Components

Wiring

Common Connections:

Writing the Code

Subscribe to our newsletter