const int buttonPin = 12;

void setup() {
    Serial.begin(9600);     
    pinMode(buttonPin, INPUT); 
}

void loop() {
    Serial.println("Druk op de knop...");
    
    while (digitalRead(buttonPin) == LOW);
    
    unsigned long duration = pulseIn(buttonPin, HIGH);
    
    Serial.print("Knop ingedrukt voor: ");
    Serial.print(duration / 1000.0);
    Serial.println(" ms");
    
    delay(500);
}