// Codes nach ISO-8859-1 (Westuropäischer Zeichensatz)

#define ae 0xE4
#define oe 0xF6
#define ue 0xFC
#define AE 0xC4
#define OE 0xD6
#define UE 0xDC
#define sz 0xDF

void setup() {
  char TextA[19] = {'h', 'e', 'i', sz, 'e', 'n','\n','S','t','e','u','e','r','c','o','d','e','\n','\0'};
  char TextB[8] = {ae,oe,ue,AE,OE,UE,sz,'\0'};
  
  Serial.begin(115200);
  Serial.print(TextA);
  Serial.println(TextB);
}

void loop() {
  // put your main code here, to run repeatedly:

}