long oldtime;
long timegap;
int pin = 13;
int state = LOW;
int counter= 0;

void setup(){
 Serial.begin(9600);
  pinMode(pin, OUTPUT);
  attachInterrupt(0, blink, RISING);
}
void loop(){
 
 // Serial.print(oldtime);
  timegap= millis()-oldtime;
  if(timegap>1000){
   // Serial.print(timegap);
    Serial.print(counter,BYTE);
    counter=0;
    oldtime = millis();
    }
  //Serial.println(time);
  // wait a second so as not to send massive amounts of data
 // delay(1000);
}
void blink()
{
  state = !state;
  digitalWrite(pin, state);
  counter++;
}