INTERRUPT-ARDUINO

Pulse counting using external interrupt interrupt

int c=0;
void setup()
{
  attachInterrupt(0, blink, FALLING);
  Serial.begin(9600);
}
void loop()
{
delay(1000);
Serial.println(c);
c=0;
}
void blink()
{
  c=c+1;
}

UART INTERRUPT

//led blinking will off when interrupt occur
int a=0;
void setup() {
  Serial.begin(9600);
pinMode(13,OUTPUT);
}
void loop()
{
  if(a==0)
  {
 digitalWrite(13,HIGH);
 delay(500);
 digitalWrite(13,LOW);
 delay(500);
  }
  else
  digitalWrite(13,LOW);
}
void serialEvent()
{
 // while (Serial.available()) {
 // Serial.write(Serial.read() );
 a=1;
   //}
 }