#define BUTTON_PIN 9
#define LED_PIN 3

void setup() {
pinMode(BUTTON_PIN, INPUT);
pinMode(LED_PIN, OUTPUT);
}

void loop() {
digitalWrite(LED_PIN, LOW);
while(digitalRead(BUTTON_PIN)==HIGH);
while(digitalRead(BUTTON_PIN)==LOW);
while(digitalRead(BUTTON_PIN)==HIGH)
{
  digitalWrite(LED_PIN,!digitalRead(LED_PIN));
  milliSecondDelay(1000);
}

}
void milliSecondDelay(uint16_t ms) {

    uint16_t i;

    for (i = 0; i < ms; i++) {
      microSecondDelay(1000);
    }

} // end millSecond
void microSecondDelay(uint16_t us) {

    uint16_t i;

    for (i = 0; i < us; i++) {
      asm volatile("nop");
      asm volatile("nop");
      asm volatile("nop");
      asm volatile("nop");
      asm volatile("nop");
      asm volatile("nop");
      asm volatile("nop");
      asm volatile("nop");
      asm volatile("nop");
      i+i;
    } 
}