#define Btn1_GPIO 4
int counter;
int speed;
const long interval = 1000;
unsigned long previousMillis = 0;

void setup()
{
  pinMode(Btn1_GPIO, INPUT);
  attachInterrupt(Btn1_GPIO, SW_DETECT, RISING);
  Serial.begin(9600);
}

void loop()
{
  unsigned long currentMillis = millis();
  //to calculate speed
  if(currentMillis = previousMillis >= interval) {
     previousMillis = currentMillis;
     speed=counter/10;
     counter=0;
}
Serial.println(counter);
Serial.println(speed);
delay(500);

}

//interrupt call function
void SW_DETECT()
{
  counter++;

}