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Robotics Ultrasonic — Free Robotics Tutorial

Learn Robotics Ultrasonic in Robotics with a free, beginner-friendly tutorial, examples and practice for Indian students on Syllab.in.

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TL;DR: Learn Robotics Ultrasonic in Robotics with a free, beginner-friendly tutorial, examples and practice for Indian students on Syllab.in.

Written & reviewed by the Syllab.in Academic Team (CBSE/NCERT subject experts) · Updated Jul 14, 2026

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Robotics Ultrasonic in Robotics

Ultrasonic sensors emit high-frequency sound waves (40 kHz) and measure the time it takes for echoes to return. Distance = speed of sound × time / 2.

Range: typically 2 cm to 4 meters. Very reliable in open air but fails in foggy/dusty conditions. No moving parts — robust and long-lasting.

Most common module: HC-SR04 with 4 pins: VCC (5V), GND, TRIG (send pulse), ECHO (receive pulse).

Robotics Ultrasonic — Syntax

// HC-SR04 Ultrasonic
const int trigPin = 4;
const int echoPin = 3;

digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);

long duration = pulseIn(echoPin, HIGH);
int distance = duration * 0.034 / 2;  // cm

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