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Distance Sensor (Ultrasonic HC-SR04) | NexaLearn IoT Lab | NexaLearn

Sensors30 دقيقة

Distance Sensor (Ultrasonic HC-SR04)

Measuring distance in centimeters, just like bats do.

Lesson Content

The ultrasonic sensor contains a 'speaker' that sends a sound pulse (Trig) and a 'microphone' that listens for the returning echo (Echo). The speed of sound is known (340 m/s). By measuring the time the pulse takes to travel out and come back, Arduino divides by 2 to calculate the distance accurately.

Components Needed

Arduino UnoHC-SR04أسلاك

Wiring Notes

VCC to 5V, GND to GND, Trig to pin 9, Echo to pin 10.

Code Example

const int trigPin = 9;
const int echoPin = 10;

void setup() {
  Serial.begin(9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
}
void loop() {
  digitalWrite(trigPin, LOW); delayMicroseconds(2);
  digitalWrite(trigPin, HIGH); delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  long duration = pulseIn(echoPin, HIGH);
  int distance = duration * 0.034 / 2;
  Serial.print("Distance: "); Serial.println(distance);
  delay(500);
}

Common Mistakes

Connecting Trig as input and Echo as output by mistake, causing the reading to always be 0.

Try in Simulator

Open in Wokwi Simulator

Next Lesson

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