int val = 0;
int led_pin = 7;
int btn_pin = 8; 

void setup() {
  // initialize digital pin 13 as an output.
  pinMode(led_pin, OUTPUT);
  pinMode(btn_pin, INPUT_PULLUP);
}

void loop() 
{
val = digitalRead(8);
   if (val == LOW) 
   {           
       digitalWrite(led_pin, HIGH);         
       delay(90);                              
       digitalWrite(led_pin, LOW);          
       delay(90);                             
   } 
   else if(val == HIGH)
   {
      digitalWrite(led_pin, LOW); 
      delay(500); 
   } 
}