backpack

#define SensorLED     13
#define SensorINPUT   3  //Connect the sensor to digital Pin 3 which is Interrupts 1.

unsigned char state = 0;
int cnt = 0;

void setup()
{
  pinMode(SensorLED, OUTPUT);
  pinMode(SensorINPUT, INPUT);
  attachInterrupt(1, blink, CHANGE);// Trigger the blink function when the falling edge is detected
  Serial.begin(9600);
}
void loop()
{
  if (state != 0)
  {
    state = 0;
    cnt ++;

    Serial.println(cnt);
    digitalWrite(SensorLED, HIGH);
    // delay(500);
  }
  else
    digitalWrite(SensorLED, LOW);
    delay(1);
}

void blink()//Interrupts function
{
  state++;
}