HC-SR04 Ultrasonic Sensor Module

The HC-SR04 Ultrasonic Sensor Module measures distance the same way bats navigate – by sending out a high-frequency sound pulse and timing how long it takes to bounce back. Two transducers handle this: one transmits a 40kHz ultrasonic burst, and the other listens for the returning echo, with the time delay between the two converted into a precise distance measurement.

To take a reading, hold the trigger pin high for 10 microseconds and then release it; this fires the ultrasonic pulse, and the echo pin then goes high for a duration proportional to the round-trip travel time of the sound wave to the target and back. While the sensor is theoretically capable of measuring from 2cm out to 4 meters, a practical, reliable range of roughly 75-80cm is more typical in real-world use. It is inexpensive, easy to interface, and requires very little power, making it a popular choice for water-depth measurement, robot obstacle avoidance, and parking-assist systems.

• Operating Voltage – +5V
• Operating Current – Less than 15mA
• Theoretical Range – 2cm to 4m
• Practical Range – 2cm to 80cm
• Accuracy – 3mm
• Measuring Angle – Less than 15°
• Trigger Pulse – 10μs high to initiate measurement

Affordable and easy to interface with any microcontroller, the HC-SR04 Ultrasonic Sensor Module is a proven choice for distance sensing in robotics and automation projects.