How to Implement the HC-SR04 Ultrasonic Sensor in Arduino Projects The HC-SR04 is a popular ultrasonic sensor used to measure distances. It works by emitting a sound wave and measuring the time it takes for the wave to bounce back from an object. Here’s how it operates:

Components:

1. Trigger Pin (T): Sends a pulse to start the measurement.
2. Echo Pin (E): Receives the reflected sound wave after it bounces off an object.
3. VCC: Powers the sensor (usually 5V).
4. GND: Ground connection.

Working Principle:

1. When you send a pulse (10 µs) to the Trigger Pin, the sensor sends out an ultrasonic wave at 40 kHz.
2. The wave travels through the air, hits an object, and bounces back.
3. The Echo Pin then receives the reflected wave, and the sensor calculates the time between sending and receiving the pulse.
4. Using the time of flight and the speed of sound (343 m/s in air), the sensor calculates the distance to the object.

Distance Calculation:

Distance (in cm) = (Duration of Echo pulse * Speed of Sound) / 2

• The division by 2 is because the sound wave travels to the object and back.

Example Wiring (Arduino):

• VCC → 5V on Arduino
• GND → GND on Arduino
• Trigger → Pin 9 on Arduino (or any other digital pin)
• Echo → Pin 10 on Arduino (or any other digital pin)