Ich würds so lösen:
Code:
#define LED_PIN  9
#define TASTER_PIN  8
#define DELAYTIME  3000 // 3 sec
unsigned long tasterMoment;

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

void loop() {
  if(digitalRead(TASTER_PIN)) 
  { 
    tasterMoment= millis();
    digitalWrite(LED_PIN, LOW);
  }   
  if (millis() - tasterMoment >= DELAYTIME) 
  {
    digitalWrite(LED_PIN, HIGH);
  }
}