const byte interruptPin1 = 3;
unsigned long startPulseTime;
unsigned long endPulseTime;
unsigned long endSeqTime;
int pulseCount = 0;
int coinFlag = 0;

void setup() {
  Serial.begin(9600);
  pinMode(interruptPin1, INPUT);
  pinMode(4, OUTPUT);
  digitalWrite(4,LOW);
  attachInterrupt(digitalPinToInterrupt(interruptPin1), coin, CHANGE);
}

void loop() {
  unsigned long currentTime = millis();
  if ( pulseCount > 0 && currentTime - endSeqTime > 300 ) {
    switch (pulseCount) {
    //tuk e sushtiq switch
    }
    pulseCount = 0;
    endSeqTime = 0;
  }
}

void coin() {
  if (coinFlag == 0) {
    startPulseTime = millis();
    coinFlag = 1;
  }
  else{
    endPulseTime = millis();
    int signalLength = endPulseTime - startPulseTime;
    if(signalLength < 52 && signalLength > 48){
      pulseCount++;
      endSeqTime = millis();
    }
    else{
    }
    coinFlag = 0;
  }
}