Ultrasonic Sensor

What is Ultrasonic Sensor HC-SR04?

An ultrasonic sensor is use to measure the distance to an object using sound waves. It provides measurements of the time that takes the sound to fling something and return it to the sensor.

It works on sound wave frequency like sonar. They also cannot detect some objects.

HC-SR04 ultrasonic can measure a range of 2 cm to 400 cm (4 m).

This sensor has 2 openings on its front. One is the transmitter which transmits ultrasonic waves like a speaker and the other is a receiver that receives them like a microphone.

Mainly there operations are not affected by sunlight or black material, but acoustically, soft materials like cloth can be difficult to detect.

Related Articles: Interface Ultrasonic Sensor with Arduino

ultrasonic sensor

Pinout and Hardware Connections

The HC-SR04 sensor module typically has four pins. The first pin is for VCC, which connects to the power supply (5V). The second pin is the Trigger (TRIG) pin used to send a signal for initiating measurement.

The third pin is Echo (ECHO), responsible for receiving the signal back after bouncing off an object. We have the Ground (GND) pin that completes the circuit by connecting to ground.

  • Vcc to 5V of Arduino.
  • GND to GND of Arduino.
  • Trig to digital pin 13 of Arduino.
  • Echo to digital pin 12 of Arduino.

HC-SR04 Specifications

When considering the specifications of the ultrasonic sensor HC-SR04, it’s important to note its operating voltage range typically between 5V-20V. This makes it versatile for various projects. The sensor has a detection range from 2cm to 400cm with an accuracy of about 3mm, providing reliable distance measurements.

The HC-SR04 operates using sound waves, emitting ultrasonic pulses and receiving echoes to determine distances. With a frequency of around 40 kHz, these sensors are efficient in detecting objects accurately within their specified range.

Board Size43 x 20 x 15 mm
Working voltage5V DC
Operating voltage5V DC
Working Frequency40Hz
Range2 cm to 400 cm (4 m)
Measuring Angle15 degree
Trigger Input Signal10 μs TTL pulse
Echo Output SignalInput TTL lever signal and the range in proportion

How Does it Work?

The Ultrasonic Sensor HC-SR04 operates on the principle of sending and receiving ultrasonic sound waves to determine the distance between the sensor and an object. When triggered, it sends out a burst of ultrasonic waves that bounce off objects in its path back to the sensor. By measuring the time taken for the waves to return, the sensor can calculate how far away the object is.

This process involves two main components: a transmitter and a receiver. The transmitter emits high-frequency sound waves that are inaudible to humans, while the receiver picks up these echoes once they bounce back. Using this information, along with known speed of sound values, the sensor can accurately measure distances within its specified range.

Uses/Applications of Ultrasonic Sensor

  • For Measuring Distance.
  • Robotic sensing.
  • Vehicle detection for car wash and automotive assembly.
  • Use in Parking Areas.
  • Presence detection.

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