text: # -*- coding: utf-8 -*-
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  # ----------------------------------------------------------------------------#
  
  import threading
  import time
  import random
  import pint
  from liota.entities.devices.device import Device
  from liota.lib.utilities.utility import systemUUID
  
  
  class ThermistorSimulated(Device):
      """
      Simulated Thermistor Device.
      """
  
      def __init__(self, name, u=5.0, r0=3000, interval=5, ureg=None):
          super(ThermistorSimulated, self).__init__(
              name=name,
              entity_id=systemUUID().get_uuid(name),
              entity_type="ThermistorSimulated"
          )
  
          self.u = u                  # Total voltage
          self.r0 = r0                # Reference resistor
          self.ux = self.u / 2        # Initial voltage on thermistor
          self.c1 = 1.40e-3
          self.c2 = 2.37e-4
          self.c3 = 9.90e-8
          self.interval = interval
          self.ureg = None
          if isinstance(ureg, pint.UnitRegistry):
              self.ureg = ureg
          else:
              self.ureg = pint.UnitRegistry()
          self.run()
  
      def run(self):
          self.th = threading.Thread(target=self.simulate)
          self.th.daemon = True
          self.th.start()
  
      # -----------------------------------------------------------------------
      # This method randomly changes some state variables in the model every a
      # few seconds (as is defined as interval).
  
      def simulate(self):
          while True:
              # Sleep until next cycle
              time.sleep(self.interval)
  
              self.ux = min(
                  max(
                      self.ux +
                      random.uniform(-0.01, 0.01) * self.interval,
                      1.5
                  ), 3.5
              )
  
      # -----------------------------------------------------------------------
      # These methods are used to access the state of the simulated physical
      # object. A typical caller is the sampling method for a metric in a Liota
      # application.
  
      def get_u(self):
          return self.ureg.volt * self.u
  
      def get_r0(self):
          return self.ureg.ohm * self.r0
  
      def get_ux(self):
          return self.ureg.volt * self.ux
  
      def get_c1(self):
          return self.c1 / self.ureg.kelvin
  
      def get_c2(self):
          return self.c2 / self.ureg.kelvin
  
      def get_c3(self):
          return self.c3 / self.ureg.kelvin
  