Distance Display

Note

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Kit purchase

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

Name	Includes ESP32 board	PURCHASE LINK
ESP32 Ultimate Starter Kit	ESP32 WROOM 32E +	BUY
Universal Maker Sensor Kit		BUY

Course Introduction

In this project, we use an ultrasonic sensor and an I2C 1602 LCD with an Arduino Nano ESP32 board to create a real-time distance measurement display system.

The ultrasonic sensor continuously measures the distance to an obstacle, and the result is shown on the LCD screen in centimeters.

The system updates the display approximately every 800 milliseconds, making it suitable for simple proximity detection applications.

Note

If this is your first time working with an ESP32 project, we recommend downloading and reviewing the basic materials first.

Required Components

In this project, we need the following components:

SN	COMPONENT INTRODUCTION	QUANTITY	PURCHASE LINK
1	Arduino Nano ESP32	1
2	USB Type-C cable	1
3	Breadboard	1	BUY
4	Wires	Several	BUY
5	Ultrasonic Sensor Module	1	BUY
6	I2C LCD 1602	1	BUY

Wiring

Common Connections:

I2C LCD 1602
- SDA: Connect to D2 on the ESP32.
- SCL: Connect to D3 on the ESP32.
- GND: Connect to GND on the ESP32 Extension Board.
- VCC: Connect to 5V on the ESP32 Extension Board.
Ultrasonic Sensor Module
- Trig: Connect to D7 on the ESP32.
- Echo: Connect to D8 on the ESP32.
- GND: Connect to GND on the ESP32 Extension Board.
- VCC: Connect to 3.3V on the ESP32 Extension Board.

Writing the Code

Note

You can copy this code into Arduino IDE.
To install the library, use the Arduino Library Manager and search for LiquidCrystal I2C and install it.
Don’t forget to select the board(Arduino Nano ESP32) and the correct port before clicking the Upload button.

#include <Wire.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 16, 2);  // I2C address 0x27, 16 columns, 2 rows

// Ultrasonic sensor pins (Dx labels for Arduino Nano ESP32)
const int echoPin = D8;   // HC-SR04 ECHO (through voltage divider!)
const int trigPin = D9;   // HC-SR04 TRIG

// PulseIn timeout (30ms ~ 5m max range)
const uint32_t ECHO_TIMEOUT_US = 30000;

void setup() {
  // Init serial
  Serial.begin(115200);
  delay(300);

  Serial.println("Ultrasonic + LCD test (I2C on D2/D3)");

  // Ultrasonic pins
  pinMode(echoPin, INPUT);
  pinMode(trigPin, OUTPUT);
  digitalWrite(trigPin, LOW);

  // -------- I2C init on D2 (SDA), D3 (SCL) --------
  Wire.begin(D2, D3);   // SDA = D2, SCL = D3
  // -----------------------------------------------

  lcd.init();
  lcd.clear();
  lcd.backlight();

  lcd.setCursor(0, 0);
  lcd.print("Distance:");
}

void loop() {
  float distance = readDistanceCm();  // distance in cm, -1 means timeout/no echo

  // Serial debug output
  if (distance < 0) {
    Serial.println("Ultrasonic: No Echo");
  } else {
    Serial.print("Ultrasonic distance: ");
    Serial.print(distance, 1);
    Serial.println(" cm");
  }

  lcd.setCursor(0, 1);
  lcd.print("                "); // clear line

  lcd.setCursor(0, 1);
  if (distance < 0) {
    lcd.print("No Echo");
  } else {
    lcd.print(distance, 1);
    lcd.print(" cm");
  }

  delay(800);
}

// Read distance in cm, returns -1 if no echo (timeout)
float readDistanceCm() {
  // Trigger pulse
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Read echo pulse width with timeout
  uint32_t duration = pulseIn(echoPin, HIGH, ECHO_TIMEOUT_US);
  if (duration == 0) return -1.0f;

  // Convert to cm
  return (float)duration / 58.0f;
}