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Ultrasonic

Technical name: HC-SR04

More precise than IR sensor

Working principle: Reflection of soundwaves

Ultrasonic waves travel faster than speed of audible sound

Range: 3cm to 4m

Accuracy: 3mm

Components

  • Emitter

  • Emitter sends out an Ultrasonic pulse at 40 kHz which travels through the air, and returns if it bounces back from an object.

  • Receiver

Measurement

Measures distance of object by emitting Ultrasonic sound waves, and converts reflected sound into electrical signal, and then by calculating the travel time & speed of sound, the distance can be calculated. $$ D = S \times \dfrac{t}{2} $$

Pins

  • VCC: +5v
  • GND
  • TRIG: Emitter (D3)
  • ECHO: Receiver

image-20240222001729823

Code

int emit_duration = 10; // microseconds
long speed = 330; // m/s
long time;

void setup() {
  pinMode(2, OUTPUT); // trig
  pinMode(3, INPUT); // echo

  Serial.begin(9600);
}
void loop() {
  // emit ultrasonic waves for 10 microsec
  digitalWrite(2, HIGH);
  delayMicroseconds(emit_duration);

  digitalWrite(2, LOW);
  delayMicroseconds(emit_duration);

  time = pulseIn(3, HIGH); // microseconds
  time /= 1000 * 1000; // seconds

  distance = speed * (time/2);

  delay(5000);
}
Last Updated: 2024-05-12 ; Contributors: AhmedThahir

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