(ชิ้นงานที่2ของเดือน ก.ค)Arduino Whistle Detector Switch using Sound Sensor

#include 

void setup() {
  Serial.begin(9600);
  FreqMeasure.begin(); //Measures on pin 8 by default
  pinMode(LED_BUILTIN, OUTPUT);
}

double sum=0;
int count=0;
bool state = false;
float frequency;
int continuity =0;

void loop() {
  if (FreqMeasure.available()) {
    // average several reading together
    sum = sum + FreqMeasure.read();
    count = count + 1;
    if (count > 100) {
      frequency = FreqMeasure.countToFrequency(sum / count);
      Serial.println(frequency);
      sum = 0;
      count = 0;
    }
  }

    if (frequency>1800 && frequency<2000)
    { continuity++; Serial.print("Continuity -> "); Serial.println(continuity); frequency=0;}

    if (continuity >=3 && state==false)
      {state = true; continuity=0; Serial.println("Light Turned ON"); delay(1000);}

    if (continuity >=3 && state==true)
      {state = false; continuity=0; Serial.println("Light Turned OFF"); delay(1000);}

    digitalWrite(LED_BUILTIN, state);
}