Added motor braking bugfix by Steve Castellotti.

Got rid of too much whitespace in motor module.

nxt/motor.py

@@ -75,68 +75,59 @@ def get_output_state(self):
         def reset_position(self, relative):
             self.brick.reset_motor_position(self.port, relative)
 
-    def update(self, power, tacho_limit, braking=False):
-        '''Use this to run a motor. power is a value between -127 and 128, tacho_limit is the
-number of degrees to apply power for. Braking is wether or not to stop the motor
-after turning the specified degrees (Under construction).'''
+    def update(self, power, tacho_limit, braking=False, max_retries=5):
+        '''Use this to run a motor. power is a value between -127 and 128, tacho_limit is
+the number of degrees to apply power for (unreliable). Braking is wether or not
+to stop the motor after turning the specified degrees. max_retries is the
+maximum times an internal loop of the braking function runs, so it doesn't get
+caught in an infinite loop.'''
 
         if braking:
             direction = (power > 0)*2-1
             self.get_output_state()
             starting_tacho_count = self.tacho_count
-
             self._debug_out('tachocount: '+str(starting_tacho_count))
-
             tacho_target = starting_tacho_count + tacho_limit*direction
-
             self._debug_out('tacho target: '+str(tacho_target))
 
         self.mode = MODE_MOTOR_ON
         self.run_state = RUN_STATE_RUNNING
         self.power = power
         self.tacho_limit = tacho_limit
-
         self._debug_out('Updating motor information...')
 
         if braking:
-
             self.update(power, 1, 0)
-
             current_tacho = 0
+            retries = 0
 
             while 1:
-
                 self._debug_out('checking tachocount...')
-
                 olderTachoCount = current_tacho
                 self.get_output_state()
                 current_tacho = self.tacho_count
-
                 self._debug_out('tachocount: '+str(current_tacho))
 
                 if current_tacho<tacho_target+10 and current_tacho>tacho_target-10:
-
                     self._debug_out('tachocount good, breaking from loop...')
-
                     break
-
                 else:
                     if current_tacho==olderTachoCount: #motor hasn't moved
-
                         self._debug_out('tachocount bad, giving extra power...')
-
+                        retries = retries + 1
                         self.update(power, 1, 0)
                     else:
                         self._debug_out('tachocount bad, waiting...')
 
+                if (retries == max_retries):
+                    self._debug_out('max retries reached, breaking from loop...')
+                    break
+
             self._debug_out('going in reverse...')
-
             self.update(direction*60, 1)
             time.sleep(0.01)
             self.mode = MODE_BRAKE
             self.set_output_state()
-
             self._debug_out('difference from goal: '+str(self.get_output_state()[7]-tacho_target))
-
         self.set_output_state()
         self._debug_out('Updating finished. ending tachocount: '+str(self.get_output_state()[7]))