Merge pull request #2 from arduino/thread_fix

Thread fix

Author: gbr1

arduino_alvik.py

@@ -13,6 +13,14 @@
 
 class ArduinoAlvik:
 
+    _update_thread_running = False
+    _update_thread_id = None
+
+    def __new__(cls):
+        if not hasattr(cls, 'instance'):
+            cls.instance = super(ArduinoAlvik, cls).__new__(cls)
+        return cls.instance
+
     def __init__(self):
         self.packeter = ucPack(200)
         self.left_wheel = _ArduinoAlvikWheel(self.packeter, ord('L'))
@@ -22,8 +30,6 @@ def __init__(self):
                                             rgb_mask=[0b00000100, 0b00001000, 0b00010000])
         self.right_led = _ArduinoAlvikRgbLed(self.packeter, 'right', self.led_state,
                                              rgb_mask=[0b00100000, 0b01000000, 0b10000000])
-        self._update_thread_running = False
-        self._update_thread_id = None
         self.battery_perc = None
         self.touch_bits = None
         self.behaviour = None
@@ -64,15 +70,18 @@ def _begin_update_thread(self):
         Runs robot background operations (e.g. threaded update)
         :return:
         """
-        self._update_thread_running = True
-        self._update_thread_id = _thread.start_new_thread(self._update, (1,))
 
-    def _stop_update_thread(self):
+        if not self.__class__._update_thread_running:
+            self.__class__._update_thread_running = True
+            self.__class__._update_thread_id = _thread.start_new_thread(self._update, (1,))
+
+    @classmethod
+    def _stop_update_thread(cls):
         """
         Stops the background operations
         :return:
         """
-        self._update_thread_running = False
+        cls._update_thread_running = False
 
     def stop(self):
         """
@@ -220,7 +229,7 @@ def _update(self, delay_=1):
         :return:
         """
         while True:
-            if not self._update_thread_running:
+            if not ArduinoAlvik._update_thread_running:
                 break
             if self._read_message():
                 self._parse_message()

examples/leds_setting.py

@@ -37,4 +37,5 @@
         sleep_ms(1000)
     except KeyboardInterrupt as e:
         print('over')
+        alvik.stop()
         sys.exit()

examples/message_reader.py

@@ -23,5 +23,5 @@
     except KeyboardInterrupt as e:
         print('over')
         alvik.stop()
-        break
-sys.exit()
+        sys.exit()
+

examples/read_color_sensor.py

@@ -13,5 +13,5 @@
         sleep_ms(100)
     except KeyboardInterrupt as e:
         print('over')
-        break
-sys.exit()
+        alvik.stop()
+        sys.exit()

examples/read_touch.py

@@ -27,5 +27,5 @@
         sleep_ms(100)
     except KeyboardInterrupt as e:
         print('over')
-        break
-sys.exit()
+        alvik.stop()
+        sys.exit()

examples/set_pid.py

@@ -14,5 +14,5 @@
         sleep_ms(100)
     except KeyboardInterrupt as e:
         print('over')
-        break
-sys.exit()
+        alvik.stop()
+        sys.exit()