Ultrasonic Module


  • TRIG: Trigger Pulse Input

  • ECHO: Echo Pulse Output

  • GND: Ground

  • VCC: 5V Supply

This is the HC-SR04 ultrasonic distance sensor, providing non-contact measurement from 2 cm to 400 cm with a range accuracy of up to 3 mm. Included on the module is an ultrasonic transmitter, a receiver and a control circuit.

You only need to connect 4 pins: VCC (power), Trig (trigger), Echo (receive) and GND (ground) to make it easy to use for your measurement projects.


  • Working Voltage: DC5V

  • Working Current: 16mA

  • Working Frequency: 40Hz

  • Max Range: 500cm

  • Min Range: 2cm

  • Trigger Input Signal: 10uS TTL pulse

  • Echo Output Signal: Input TTL lever signal and the range in proportion

  • Connector: XH2.54-4P

  • Dimension: 46x20.5x15 mm


The basic principles are as follows:

  • Using IO trigger for at least 10us high level signal.

  • The module sends an 8 cycle burst of ultrasound at 40 kHz and detects whether a pulse signal is received.

  • Echo will output a high level if a signal is returned; the duration of the high level is the time from emission to return.

  • Distance = (high level time x velocity of sound (340M/S)) / 2



  • us / 58 = centimeters distance

  • us / 148 = inch distance

  • distance = high level time x velocity (340M/S) / 2


This module should not be connected under power up, if necessary, let the module’s GND be connected first. Otherwise, it will affect the work of the module.

The area of the object to be measured should be at least 0.5 square meters and as flat as possible. Otherwise, it will affect results.