Parking Sensor 1.0

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

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

In this lesson, we’ll build a basic parking assistance system (v1.0) using an Ultrasonic Sensor Module, MAX7219 Dot Matrix Module, and a passive buzzer Module with Arduino board.

As an obstacle approaches the ultrasonic sensor, the buzzer will emit warning sounds that become increasingly rapid, while the dot matrix display will show a rough visual representation of the obstacle’s proximity.

Note

If this is your first time working with an Arduino 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 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	MAX7219 Dot Matrix Module	1	BUY
7	Alarm Sound Module	1	BUY

Wiring

Common Connections:

Passive Buzzer Module
- VCC: Connect to breadboard’s red power bus.
- I/O: Connect to 3 on the Arduino.
- GND: Connect to breadboard’s negative power bus.
MAX7219 Dot Matrix Module
- CLK: Connect to 11 on the Arduino.
- CS: Connect to 10 on the Arduino.
- DIN: Connect to 12 on the Arduino.
- GND: Connect to breadboard’s negative power bus.
- VCC: Connect to breadboard’s red power bus.
Ultrasonic Sensor Module
- Trig: Connect to 5 on the Arduino.
- Echo: Connect to 4 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 LedControl and install it.
Don’t forget to select the board(Arduino UNO R4 WIFI) and the correct port before clicking the Upload button.

#include <LedControl.h>

// Pin definitions
const int echoPin = 4;    // Ultrasonic sensor Echo pin
const int trigPin = 5;    // Ultrasonic sensor Trig pin
const int buzzerPin = 3;  // Buzzer pin

// Initialize LedControl for MAX7219: DIN=12, CLK=11, CS=10, 1 device
LedControl lc = LedControl(12, 11, 10, 1);

int previousColumnsLit = 0;       // Last number of lit columns

// Buzzer non-blocking control variables
unsigned long lastBeepTime = 0;   // Timestamp of last beep toggle
bool isBeepOn = false;            // Current buzzer state
unsigned long beepInterval = 500; // Interval for buzzer toggle in ms

void setup() {
  Serial.begin(9600);            // Start serial communication at 9600 baud
  pinMode(echoPin, INPUT);       // Set echoPin as input
  pinMode(trigPin, OUTPUT);      // Set trigPin as output
  pinMode(buzzerPin, OUTPUT);    // Set buzzerPin as output

  lc.shutdown(0, false);         // Wake up MAX7219
  lc.setIntensity(0, 8);         // Set brightness level (0-15)
  lc.clearDisplay(0);            // Clear the display
}

void loop() {
  // 1. Read distance and update LED columns
  float distance = readSensorData();
  int columnsToLight = calculateColumnsToLight(distance);
  displayColumnsWithTransition(previousColumnsLit, columnsToLight);
  previousColumnsLit = columnsToLight;

  // 2. Update beep speed based on distance, then toggle buzzer
  updateBeepInterval(distance);
  updateBeepState();

  // 3. Print distance for debugging
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");
}

// Read distance from ultrasonic sensor in centimeters
float readSensorData() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);                 // Ensure clean LOW pulse
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);                // Send 10µs HIGH pulse
  digitalWrite(trigPin, LOW);

  float duration = pulseIn(echoPin, HIGH); // Read echo time in µs
  float distance = duration / 58.0;        // Convert to cm (approx.)
  return distance;
}

// Map distance to number of LED matrix columns (0 to 8)
int calculateColumnsToLight(float distance) {
  if (distance > 20) {                  // If farther than 20 cm
    return 0;                           // No columns lit
  } else {
    int cols = (20 - distance) / 2;     // Every 2 cm closer lights one column
    return constrain(cols, 0, 8);       // Limit result between 0 and 8
  }
}

// Animate LED columns lighting/unlighting with small blocking delay
void displayColumnsWithTransition(int previousColumns, int currentColumns) {
  if (currentColumns > previousColumns) {
    // Light up new columns from left to right
    for (int col = previousColumns; col < currentColumns; col++) {
      for (int row = 0; row <= col; row++) {
        lc.setLed(0, col, row, true);  // Turn on LED at (col, row)
      }
      delay(50);                        // Small delay for animation effect
    }
  } else if (currentColumns < previousColumns) {
    // Turn off columns from left to right
    for (int col = previousColumns - 1; col >= currentColumns; col--) {
      for (int row = 0; row <= col; row++) {
        lc.setLed(0, col, row, false); // Turn off LED at (col, row)
      }
      delay(50);                        // Small delay for animation effect
    }
  }
}

// Set beep interval based on distance:
// <6 cm   -> fast beep (100 ms on/off)
// <12 cm  -> medium beep (300 ms on/off)
// <18 cm  -> slow beep (500 ms on/off)
// >=18 cm -> no beep
void updateBeepInterval(float distance) {
  if (distance < 6) {
    beepInterval = 100;   // Fast beep: 100 ms on, 100 ms off
  } else if (distance < 12) {
    beepInterval = 300;   // Medium beep: 300 ms on, 300 ms off
  } else if (distance < 18) {
    beepInterval = 500;   // Slow beep: 500 ms on, 500 ms off
  } else {
    beepInterval = 0;     // Disable beep
    noTone(buzzerPin);
    isBeepOn = false;
  }
}

// Toggle buzzer on/off without blocking using millis()
void updateBeepState() {
  if (beepInterval == 0) {
    return;               // No beep needed
  }

  unsigned long currentMillis = millis();
  if (currentMillis - lastBeepTime >= beepInterval) {
    if (isBeepOn) {
      noTone(buzzerPin);  // Turn off buzzer
      isBeepOn = false;
    } else {
      tone(buzzerPin, 1000); // Turn on buzzer at 1 kHz
      isBeepOn = true;
    }
    lastBeepTime = currentMillis; // Reset timestamp
  }
}