HC-SR04 - ultrasonic distance sensor up to 5 meters

Description

The HC-SR04 ultrasonic sensor module is a popular solution for measuring distances, used in projects based on Arduino, Raspberry Pi, STM32 or ESP32 in fields such as robotics, automation or security systems. It enables precise measurement of distances in the range of 2 cm to 500 cm with a resolution of 3 mm, making it an ideal choice for detecting obstacles, measuring distances or creating collision avoidance systems.

How does the ultrasonic distance sensor work?

The HC-SR04 module works by emitting ultrasonic waves at a frequency of 40 kHz by the built-in transmitter. These waves propagate in the air and reflect off the obstacle they encounter. The receiver, located next to the transmitter, records the return of the reflected signal. The distance is calculated based on the time between sending and receiving the signal. This value depends on the speed of sound in air (approx. 343 m/s) and the time it takes to travel from the sensor to the obstacle and back.

How to connect the HC-SR04 sensor?

The HC-SR04 module has four pins: VCC, Trigger, Echo and GND.

• VCC should be connected to the 5 V power supply.
• GND to the system ground.
• The trigger is connected to the digital output of the microcontroller, which is responsible for sending the initiating pulse.
• The echo is connected to the digital input, which records the signal return time.

The measurement process begins with the microcontroller sending a short pulse to the Trigger pin. The sensor generates an ultrasonic signal that is reflected from the obstacle, and the result is returned as a signal to the Echo pin. The microcontroller converts the time from emission to reception of the signal into the distance from the obstacle.

Applications of the HC-SR04 ultrasonic distance sensor

The HC-SR04 sensor is widely used in various engineering and hobby projects. It is most often used in:

Mobile robotics - for detecting and avoiding obstacles, as well as navigation of autonomous vehicles.
Automation systems – in monitoring distances, e.g. in automatic door opening systems
Security systems – as a motion detection sensor, for monitoring space or creating alarms.
DIY projects – in various home electronics projects, such as smart devices, measuring systems or educational projects.

Features

• Measurement range: 2 cm – 500 cm
• Resolution: 3 mm
• Detection angle: 15°
• Power supply: 5 V
• Interface: 4 pins (VCC, Trigger, Echo, GND)
• Ultrasonic frequency: 40 kHz
• Current consumption: < 2 mA
• Compatibility: Arduino, Raspberry Pi, other microcontroller platforms