Arduino Project

Arduino Parking Sensor with Ultrasonic Sensor V5

Kit purchase

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

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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
Ultimate Sensor Kit	Arduino Uno R4 Minima	BUY
Universal Maker Sensor Kit	×	BUY

Course Introduction

In this lesson, we’ll build a basic parking assistance system using an Ultrasonic Sensor Module, 16x2 LCD, LED, and a buzzer with Arduino.

As an obstacle moves closer, the LED and buzzer will warn increasingly faster, while the LCD displays the real-time distance and warning status.

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	Ultrasonic Sensor Module	1	BUY
6	LED	1	BUY
7	Active Buzzer	1	×
8	1kΩ resistor	1	BUY
9	I2C LCD 1602	1	BUY

Wiring

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Common Connections:

LED
Connect the LED cathode to the negative power bus on the breadboard, and the LED anode to a 1kΩ resistor then to 6 on the Arduino.

Active Buzzer
＋: Connect to 3 on the Arduino.
－: Connect to breadboard’s negative power bus.

Ultrasonic Sensor Module
Trig: Connect to 11 on the Arduino.
Echo: Connect to 10 on the Arduino.
GND: Connect to breadboard’s negative power bus.
VCC: Connect to breadboard’s red power bus.

I2C LCD 1602
SDA: Connect to A4 on the Arduino.
SCL: Connect to A5 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 LiquidCrystal I2C and install it.
Don’t forget to select the board(Arduino UNO R4 WIFI) and the correct port before clicking the Upload button.

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

const int ECHO_PIN = 10;
const int TRIG_PIN = 11;

const int BUZZER_PIN = 3;
const int LED_PIN = 6;

// Create a 16x2 LCD at I2C address 0x27
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Distance thresholds in centimeters
const float STOP_DISTANCE = 5.0;
const float FAST_DISTANCE = 9.0;
const float MEDIUM_DISTANCE = 13.0;
const float MAX_DISTANCE = 17.0;

// Time between warning beeps
const unsigned long SLOW_INTERVAL = 800;
const unsigned long MEDIUM_INTERVAL = 400;
const unsigned long FAST_INTERVAL = 180;

// Each beep and LED flash lasts 100 ms
const unsigned long BEEP_DURATION = 100;

// Measure distance every 70 ms
const unsigned long MEASURE_INTERVAL = 70;

// Update the LCD every 250 ms
const unsigned long LCD_INTERVAL = 250;

// Store timing values
unsigned long lastMeasureTime = 0;
unsigned long lastBeepTime = 0;
unsigned long beepStartTime = 0;
unsigned long lastLcdTime = 0;

// Store the current distance
float distance = -1;

// Store the current beep interval
unsigned long warningInterval = 0;

// Track whether a warning beep is active
bool beepActive = false;

// Define the warning levels
enum WarningLevel {
  SAFE,
  SLOW,
  MEDIUM,
  FAST,
  STOP
};

WarningLevel currentLevel = SAFE;

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

  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(LED_PIN, OUTPUT);

  // Start with all outputs turned off
  digitalWrite(TRIG_PIN, LOW);
  digitalWrite(BUZZER_PIN, LOW);
  digitalWrite(LED_PIN, LOW);

  // Start the LCD
  lcd.init();
  lcd.backlight();

  lcd.setCursor(0, 0);
  lcd.print("Parking Sensor");

  lcd.setCursor(0, 1);
  lcd.print("Starting...");

  delay(1000);

  lcd.clear();
}

void loop() {
  unsigned long currentTime = millis();

  // Measure the distance at regular intervals
  if (currentTime - lastMeasureTime >= MEASURE_INTERVAL) {
    lastMeasureTime = currentTime;

    distance = readDistance();
    updateWarningLevel();
  }

  // Update the LED and buzzer
  updateWarningOutput();

  // Refresh the LCD at a slower rate for a steadier display
  if (currentTime - lastLcdTime >= LCD_INTERVAL) {
    lastLcdTime = currentTime;

    updateLCD();
  }
}

// Measure distance with the ultrasonic sensor
float readDistance() {
  // Send a short trigger pulse
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);

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

  digitalWrite(TRIG_PIN, LOW);

  // Measure how long the echo signal stays HIGH
  unsigned long duration = pulseIn(ECHO_PIN, HIGH, 5000);

  // Return -1 if no echo is received
  if (duration == 0) {
    return -1;
  }

  // Convert the echo time to centimeters
  return duration / 58.0;
}

// Choose the warning level based on distance
void updateWarningLevel() {
  // No valid reading
  if (distance < 0) {
    currentLevel = SAFE;
    warningInterval = 0;
    return;
  }

  // More than 17 cm: no warning
  if (distance > MAX_DISTANCE) {
    currentLevel = SAFE;
    warningInterval = 0;
  }

  // 13-17 cm: slow warning
  else if (distance > MEDIUM_DISTANCE) {
    currentLevel = SLOW;
    warningInterval = SLOW_INTERVAL;
  }

  // 9-13 cm: medium warning
  else if (distance > FAST_DISTANCE) {
    currentLevel = MEDIUM;
    warningInterval = MEDIUM_INTERVAL;
  }

  // 5-9 cm: fast warning
  else if (distance > STOP_DISTANCE) {
    currentLevel = FAST;
    warningInterval = FAST_INTERVAL;
  }

  // 5 cm or less: continuous warning
  else {
    currentLevel = STOP;
    warningInterval = 0;
  }
}

// Control the LED and buzzer without using delay()
void updateWarningOutput() {
  unsigned long currentTime = millis();

  // Safe zone: turn both outputs off
  if (currentLevel == SAFE) {
    digitalWrite(BUZZER_PIN, LOW);
    digitalWrite(LED_PIN, LOW);

    beepActive = false;
    return;
  }

  // Stop zone: keep both outputs on
  if (currentLevel == STOP) {
    digitalWrite(BUZZER_PIN, HIGH);
    digitalWrite(LED_PIN, HIGH);

    beepActive = true;
    return;
  }

  // Start a beep and LED flash
  if (!beepActive &&
      currentTime - lastBeepTime >= warningInterval) {

    beepActive = true;
    beepStartTime = currentTime;
    lastBeepTime = currentTime;

    digitalWrite(BUZZER_PIN, HIGH);
    digitalWrite(LED_PIN, HIGH);
  }

  // Turn them off after the warning pulse
  if (beepActive &&
      currentTime - beepStartTime >= BEEP_DURATION) {

    beepActive = false;

    digitalWrite(BUZZER_PIN, LOW);
    digitalWrite(LED_PIN, LOW);
  }
}

// Show the distance and warning level on the LCD
void updateLCD() {
  lcd.setCursor(0, 0);

  if (distance < 0) {
    lcd.print("Distance: ---cm ");
  } else {
    lcd.print("Distance:");

    // Keep the distance value aligned on the screen
    if (distance < 10) {
      lcd.print(" ");
    }

    lcd.print(distance, 1);
    lcd.print("cm ");
  }

  lcd.setCursor(0, 1);
  lcd.print("Status: ");

  switch (currentLevel) {
    case SAFE:
      lcd.print("SAFE   ");
      break;

    case SLOW:
      lcd.print("SLOW   ");
      break;

    case MEDIUM:
      lcd.print("MEDIUM ");
      break;

    case FAST:
      lcd.print("FAST   ");
      break;

    case STOP:
      lcd.print("STOP!  ");
      break;
  }
}

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Arduino Project

Arduino Parking Sensor with Ultrasonic Sensor V5

Kit purchase

Course Introduction

Required Components

Wiring

Common Connections:

Writing the Code

Arduino Project

Arduino Parking Sensor with Ultrasonic Sensor V5

Kit purchase

Course Introduction

Required Components

Wiring

Common Connections:

Writing the Code

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