Source Code for Module LightSensor

  1  # LightSensor.java 
  2   
  3  ''' 
  4  Class that represents a light sensor. 
  5   
  6   This software is part of the raspibrick module. 
  7   It is Open Source Free Software, so you may 
  8   - run the code for any purpose 
  9   - study how the code works and adapt it to your needs 
 10   - integrate all or parts of the code in your own programs 
 11   - redistribute copies of the code777 
 12   - improve the code and release your improvements to the public 
 13   However the use of the code is entirely your responsibility. 
 14   ''' 
 15   
 16  from Tools import Tools 
 17  from RobotInstance import RobotInstance 
 18  import SharedConstants 
 19   
 20 -class LightSensor(): 
 21      ''' 
 22      Class that represents an light sensor. 
 23      ''' 
 24 -    def __init__(self, id, **kwargs): 
 25          ''' 
 26          Creates a light sensor instance with given id. 
 27          IDs: 0: front left, 1: front right, 2: rear left, 3: rear right 
 28          The following global constants are defined: 
 29          LS_FRONT_LEFT = 0, LS_FRONT_RIGHT = 1, LS_REAR_LEFT = 2, LS_REAR_RIGHT = 3. 
 30          @param id: the LightSensor identifier 
 31          ''' 
 32          self.id = id 
 33          self.sensorState = "DARK" 
 34          self.sensorType = "LightSensor" 
 35          self.triggerLevel = 500 
 36          self.brightCallback = None 
 37          self.darkCallback = None 
 38          self.isRegistered = False 
 39          for key in kwargs: 
 40              if key == "bright": 
 41                  self.brightCallback = kwargs[key] 
 42              elif key == "dark": 
 43                  self.darkCallback = kwargs[key] 
 44          robot = RobotInstance.getRobot() 
 45          if robot == None:  # deferred registering, because Robot not yet created 
 46              RobotInstance._sensorsToRegister.append(self) 
 47          else: 
 48              if self.brightCallback != None or self.darkCallback != None: 
 49                  robot.registerSensor(self) 
 50          Tools.debug("LightSensor instance with ID " + str(id) + " created") 
 51   
 52 -    def getValue(self): 
 53          ''' 
 54          Returns the current intensity value (0..1000). 
 55          @return: the measured light intensity 
 56          @rtype: int 
 57          ''' 
 58          self._checkRobot() 
 59          Tools.delay(1) 
 60          nb = self.id 
 61          if nb == 0: 
 62              nb = 1 
 63          elif nb == 1: 
 64              nb = 0 
 65          robot = RobotInstance.getRobot() 
 66          return int(self._readADC(nb) / 255.0 * 1000 + 0.5) 
 67   
 68 -    def getTriggerLevel(self): 
 69          return self.triggerLevel 
 70   
 71 -    def setTriggerLevel(self, level): 
 72          self.triggerLevel = level 
 73   
 74 -    def getSensorState(self): 
 75          return self.sensorState 
 76   
 77 -    def setSensorState(self, state): 
 78          self.sensorState = state 
 79   
 80 -    def getSensorType(self): 
 81          return self.sensorType 
 82   
 83 -    def onBright(self, v): 
 84          if self.brightCallback != None: 
 85              self.brightCallback(self.id, v) 
 86   
 87 -    def onDark(self, v): 
 88          if self.darkCallback != None: 
 89              self.darkCallback(self.id, v) 
 90   
 91 -    def _readADC(self, channel): 
 92          robot = RobotInstance.getRobot() 
 93          try: 
 94              robot._bus.write_byte(SharedConstants.ADC_I2C_ADDRESS, channel) 
 95              robot._bus.read_byte(SharedConstants.ADC_I2C_ADDRESS) # ignore first byte 
 96              data = robot._bus.read_byte(SharedConstants.ADC_I2C_ADDRESS) 
 97          except: 
 98              raise Exception("Exception while accessing PCF8591P I2C Expander. channel: " + str(channel)) 
 99              data = 0 
100          return data 
101   
102 -    def _checkRobot(self): 
103          if RobotInstance.getRobot() == None: 
104              raise Exception("Create Robot instance first") 
105