2021-11-01

HC-SR04 ultrasonic distance sensor module

  • How does this work, from a user perspective?

Demo with AD2

  • What is necessary to drive this module from a 3.3V MCU?

  • What information or numbers do you need to answer this?

    • module power supply (spec 5V, is 3V3 ok?)

    • output pins (MCU → module)

    • input pins (MCU ← module)

    • voltage levels (input and output)

1. Information

Fundamentals:

  • Transmit a pulse of sound (N-cycles at 40kHz)

  • Amplify the receiver transducer

  • Detect a reflected pulse

  • Returned sound travelled out then back, distance away is /2.

The original and much copied: https://www.robot-electronics.co.uk/htm/srf04tech.htm

Great article that includes measurements and thoughtful thinking: https://www.davidpilling.com/wiki/index.php/HCSR04

Datasheet + Application Note from Murata: