Ultrasonic Sensor (HC-SR04)

Ultrasonic Sensor (HC-SR04)


Ultrasonic Sensor (HC-SR04) is an electronic devices that generates or sense the ultrasound energy. It measures the distance to an object using ultrasonic sound waves. Ultrasonic waves travels faster than the speed of audible sound. It takes exact distance using a non-contact technology. There are two main parts of HC-SR04- the transmitter and the receiver. Transmitter converts electrical signal into ultrasonic waves while receiver the vice-versa

Pin Confriguation

Pin No.Pin NameDescription
1VccThe Vcc pin powers the sensor, provides +5V power supply.
2TriggerTrigger pin is an input pin.
3EchoEcho pin is an output pin
4GroundThe pin is is connected to the ground of the system.

Features of HC-SR04 Sensor

  • Operating Voltage
  • Theoretically measures the distance: 2cm to 450cm
  • Practically measuring distance:2cm to 80cm
  • Acuracy: 3mm
  • Operating frequency: 40Hz
  • Operating current: <15mA
  • Resolution:0.3cm


HC-SR04 Ultrasonic Sensor is a 4 pin module, named as Vcc, trigger, echo and ground. This sensor is very useful sensor so as to Where measure distance or sense objects are required. The module has two eye like projection in its front which is Transmitter and Receiver.

This Sensor works with formula:


  • The transmitter (trig pin) sends a signal: a high frequency sound.
  • When signal finds an object, it is reflects and transmitter (echo) receives it.

The time between the transmission and reception of signal us to calculate the distance to an object.


  • Use to avoid and detect obstacles with robots like biped robot, obstacle avoider robot, path finding etc.
  • Use to measure the distance within a wide range of 2cm to 450cm.
  • Can be used to map the objects surrounding the sensor by rotating it.
  • Detects hidden cracks in tracks, plastics, ceramics.
  • Depth measurement
  • Burglar alarms
  • Embedded system
  • Humidifiers



From all above we concluded that this sensor uses sonar to measure the distance between sensor and object. The transmitter sends a high frequency sound signal. Once signal discovers object then it reflect back to echo pin of transmitter.


Anshika Gupta

Hey I am Anshika Gupta currently pursuing my bachelors in Electronics and communication engineering. I am glad to be in this community. I am very fond technology and research. I am Global Ambassador @WomenTech Network. I believe in implementing and excelling the learning in any form to just adapt new skills. I am delighted to interact with you all here.

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