int val = 1;
int mode = 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);
}

// the loop function runs over and over again forever
void loop() {

val = digitalRead(8);
   if (val == LOW) {         // check if the input is HIGH (button released) 
      digitalWrite(led_pin, HIGH);   // turn the LED on (HIGH is the voltage level)
      delay(1000);              // wait for a second
      digitalWrite(led_pin, LOW);   // turn the LED on (HIGH is the voltage level)
      delay(1000);              // wait for a second  
  }
}