diff --git a/raspberry/roberto/Serial.py b/raspberry/roberto/Serial.py
index 5cab0d3..04baecd 100644
--- a/raspberry/roberto/Serial.py
+++ b/raspberry/roberto/Serial.py
@@ -45,24 +45,29 @@ class Serial(object):
     def reader(self):
         try:
             while self.alive and self.serialport:
-                data = self.serialport.read(self.serialport.in_waiting or 1)
+                #data = self.serialport.read(self.serialport.in_waiting or 1)
+                data = self.serialport.readline()
                 if data:
                     print(data)
+                    if isinstance(data, bytes):
+                        data = data.decode(encoding='utf8')
                     command = data[0]
                     argument = data[2:].strip()
                     if command and command in self._callbacks:
                         cb = self._callbacks[command]
                         if cb:
                             cb(argument)
+                    else:
+                        print("no callback found for command '%s'" % command)
 
         except serial.SerialException:
             pass
             #self.alive = False
             #raise
 
-    def add_callback(cmd, callback):
+    def add_callback(self, cmd, callback):
         self._callbacks[cmd] = callback
 
-    def del_callback(cmd, callback):
+    def del_callback(self, cmd, callback):
         if cmd in self._callbacks:
             del self._callbacks[cmd]