add schematic pdf

tools/test_keyboard.py

@@ -5,6 +5,7 @@ chars=" qwertzuiopü+asdfghjklöä#yxcvbnm,.-QWERTZUIOPÜ*ASDFGHJKLÖÄ'YXCVBNM;
 
 def main():
     with serial.Serial('/dev/ttyUSB0', 9200, timeout=1) as ser:
+        
 
         print("ZWÖLF BOXKÄMPFER JAGEN VIKTOR QUER ÜBER DEN GROßEN SYLTER DEICH.")
         print("zwölf boxkämpfer jagen viktor quer über den großen sylter deich.")
@@ -22,6 +23,7 @@ def main():
         ser.write(b'\r\n')
 
 
+        print("# if the text looks like the following, use_rn is turned on")
         print("Zeile1, rn")
         print("Zeile2, n")
         print("Zeile4   Zeile3, r")