Sound level meter

Overview

As you rotate the volume, the number of LEDs light up in proportion to the amount of rotation. You can also turn on the number of LEDs according to the ambient volume with the microphone.

Leaf to use

Use the following leaves.

Type	Name	Q’ty
AZ62	Connector Cover	2
AI03	MIC&VR&LED	1
AX07	Back to back	1
AP02	ESP32 MCU	1
AV04	2V~4.5V	1
AZ63	Nut Plate	2
	AAA battery holder	1
	AAA battery	3
	M2*8mm screw	2
	M2*12mm screw	2
	φ10x2mm magnet	1

Assembly

Let’s assemble leaves as shown in the figure below.

Source code

Write the following program in the Arduino IDE.

//=====================================================================
//  ESP32 Sound level meter
//
//    (c) 2020 Trillion-Node Study Group
//    Released under the MIT license
//    https://opensource.org/licenses/MIT
//
//      Rev.00 2020/08/20  First release
//=====================================================================

// LED4-6:VR level display
// LED1-3:MIC sound pressure level display

#define LED1              14            // D6  IO14
#define LED2              15            // D7  IO15
#define LED3              17            // D8  IO17
#define LED4              16            // D9  IO16
#define LED5              5             // D10 IO5
#define LED6              23            // D11 IO23
#define MIC               26            // A2  IO26
#define VR                39            // A3  IO39

unsigned int dataVR;
unsigned int dataMic;

//-----------------------------------------------
// Get VR and MIC data
//-----------------------------------------------
void getSensorData(){
    dataVR = analogRead(VR);
    dataMic = analogRead(MIC);

    Serial.println("---------------------");
    Serial.print("MIC  = ");
    Serial.println(dataMic,DEC);
    Serial.print("VR   = ");
    Serial.println(dataVR,DEC);
}

//-----------------------------------------------
// Turn the LEDs on and off according to the VR and MIC values.
//-----------------------------------------------
void dispSensorData(){
    if (dataVR < 1500){
      digitalWrite(LED4,LOW);
      digitalWrite(LED5,LOW);
      digitalWrite(LED6,LOW);
    }
    else if (dataVR >= 1500 && dataVR < 2600){
       digitalWrite(LED4,LOW);
       digitalWrite(LED5,LOW);
       digitalWrite(LED6,HIGH);
    }
    else if (dataVR >= 2600 && dataVR < 3600){
       digitalWrite(LED4,LOW);
       digitalWrite(LED5,HIGH);
       digitalWrite(LED6,HIGH);
    }
    else{
       digitalWrite(LED4,HIGH);
       digitalWrite(LED5,HIGH);
       digitalWrite(LED6,HIGH);
    }

    if (dataMic < 400){
      digitalWrite(LED1,LOW);
      digitalWrite(LED2,LOW);
      digitalWrite(LED3,LOW);
    }
    else if (dataMic >= 400 && dataMic < 600){
      digitalWrite(LED1,LOW);
      digitalWrite(LED2,LOW);
      digitalWrite(LED3,HIGH);
    }
    else if (dataMic >= 600 && dataMic < 950){
      digitalWrite(LED1,LOW);
      digitalWrite(LED2,HIGH);
      digitalWrite(LED3,HIGH);
    }
    else{
      digitalWrite(LED1,HIGH);
      digitalWrite(LED2,HIGH);
      digitalWrite(LED3,HIGH);
    }
}


void setup(){
  Serial.begin(115200);
  Serial.println("start!!");

  pinMode(LED1, OUTPUT);
  digitalWrite(LED1, LOW);
  pinMode(LED2, OUTPUT);
  digitalWrite(LED2, LOW);
  pinMode(LED3, OUTPUT);
  digitalWrite(LED3, LOW);
  pinMode(LED4, OUTPUT);
  digitalWrite(LED4, LOW);
  pinMode(LED5, OUTPUT);
  digitalWrite(LED5, LOW);
  pinMode(LED6, OUTPUT);
  digitalWrite(LED6, LOW);

  pinMode(MIC, INPUT);
  pinMode(VR, INPUT);

  // Startup test(LED)
  digitalWrite(LED1,HIGH);
  delay(200);
  digitalWrite(LED2,HIGH);
  delay(200);
  digitalWrite(LED3,HIGH);
  delay(200);
  digitalWrite(LED4,HIGH);
  delay(200);
  digitalWrite(LED5,HIGH);
  delay(200);
  digitalWrite(LED6,HIGH);
  delay(200);
  digitalWrite(LED1,LOW);
  digitalWrite(LED2,LOW);
  digitalWrite(LED3,LOW);
  digitalWrite(LED4,LOW);
  digitalWrite(LED5,LOW);
  digitalWrite(LED6,LOW);
  delay(200);
}


void loop() {
  getSensorData();
  dispSensorData();
  delay(100);
}

ESP32_Sound_Level_Meter.ino

Execution Results

When the volume is rotated, a number of LEDs will light up according to the amount of rotation. When the microphone is turned on, a number of LEDs will light up according to the ambient volume.