int TASTER_EINS = 5;  // Taste 1 
int TASTER_ZWEI = 4;  // Taste 2 
int TASTER_DREI = 7;  // Taste 3 
int TASTER_VIER = 6;  // Taste 4 

void setup() 
{ 
  Serial.begin(9600);    

  // Vorwiderstand aktivieren 
  pinMode(TASTER_EINS, INPUT_PULLUP); 
  pinMode(TASTER_ZWEI, INPUT_PULLUP); 
  pinMode(TASTER_DREI, INPUT_PULLUP); 
  pinMode(TASTER_VIER, INPUT_PULLUP); 
} 

void loop() 
{ 
  if (digitalRead(TASTER_EINS) == LOW) 
  {   
    delay(100); 
    Serial.println("Taste 1 an Pin " + String(TASTER_EINS));        
  } 

  if (digitalRead(TASTER_ZWEI) == LOW)   
  {  
    delay(100);   
    Serial.println("Taste 2 an Pin " + String(TASTER_ZWEI));     
  } 
 
  if (digitalRead(TASTER_DREI) == LOW)  
  {  
    delay(100); 
    Serial.println("Taste 3 an Pin " + String(TASTER_DREI));    
  } 

  if (digitalRead(TASTER_VIER) == LOW)   
  {  
    delay(100);  
    Serial.println("Taste 4 an Pin " + String(TASTER_VIER));    
  } 
}