Sound Sensor Interfacing with 8051

This tutorial is all about Sound Sensor Interfacing with 8051.


Before start this tutorial we should know below topics. If you know already, please go further.

Components Required

  • 8051 Development Board
  • Sound Sensor
  • LCD Module (To print the Sensor output)


Sound detection sensor module detects whether sound has exceeded a threshold value. Sound is detected via microphone and fed into an LM393 op amp. The sound level set point is adjusted via an on board potentiometer. When the sound level exceeds the set point, an LED on the module is illuminated and the output is sent low.

Product Description

  • Main chip: LM393, electret microphone
  • Working voltage: DC 4 ~ 6V
  • Has the signal output instructions
  • Single signal output.
  • Effective signal output for low level.
  • Output low level and signal light will on when there has voice.
  • Can be used for sonic lamp, with photosensitive sensors act as sound and light alarm, also can be used in the occasion of voice control and sound detection.
  • Circuit boards output switch value.

Note: This sensor only recognizes the availability of sound can not identify the size of the sound or the specific frequencies of sound.

Sound Sensor Interfacing with 8051


Sound Sensor

  • Vcc – 5v
  • Gnd – Ground
  • Vout – P1.0


  • RS – P2.0
  • RW – P2.1
  • EN – P2.2
  • Data Lines – P3.0 – P3.7

Sound Sensor Interfacing with 8051

Source Code

If this sensor detects any sound, LCD will display “Sound Detected”. You can also vary the threshold level by adjusting the Potentiometer in that sensor module.



The system can be used for home /office security purpose. When a thief or robber tries to enter the home or office, some sort of sound will be generated. It may be voice or any other sort of sound. The microphone takes the sound and sends message instantly.


The system can be used as a clapping switch. If we add the LED with a relay or BJT, the system acts as a switch. When we clapped, microphone takes the sound and comparator output goes high. As a result, BJT or relay turns on. If we connect this BJT or relay with light, fan or any electrical / electronic instruments, the system can be operated as a clapping switch.

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