Arduino Parking Sensor with Ultrasonic Sensor

The ultrasonic sensor sends a sound pulse and times the echo, like a bat. The closer the wall, the faster the beeps.

Parts you need

• Arduino Uno
• HC-SR04 ultrasonic sensor
• Piezo buzzer

Wiring

1. Sensor VCC → 5V, GND → GND
2. Trig → pin 7, Echo → pin 6
3. Pin 8 → buzzer → GND rail

Arduino code

int trig = 7;
int echo = 6;
int buzzer = 8;

void setup() {
  pinMode(trig, OUTPUT);
  pinMode(echo, INPUT);
  Serial.begin(9600);
}

void loop() {
  digitalWrite(trig, LOW);
  delayMicroseconds(2);
  digitalWrite(trig, HIGH);
  delayMicroseconds(10);
  digitalWrite(trig, LOW);

  long duration = pulseIn(echo, HIGH);
  int distance = duration / 58;
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  if (distance < 20) {
    tone(buzzer, 1000, 100);
    delay(distance * 10 + 50);
  } else {
    delay(300);
  }
}

Goal and tip

Goal: Move the obstacle closer than 20 cm to hear the warning beeps.

Tip: Try this: change 20 to 40 so the alarm starts earlier.

Run this experiment in the free simulator