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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

Application Notes

  • 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.