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  - (Re)display a recent flight
  - Display a histogram
  - Send information for a different display mode
  - Indicate that the battery is low

  Args:
    command: dictionary representing all data fields from remote.
    configuration: dictionary representing the current state of the messageboard
      configuration.
    display_mode: current display mode; only passed so that we may identify changes.
    low_battery: current battery status; only passed so that we may identify changes.
    to_parent_q: multiprocessing queue, where instructions to send back to messageboard,
      if any, can be placed.
    link: the open serial link.

  Returns:
    A 2-tuple of potentially-updated display_mode, and low_battery.
  """
  # command might update a setting; see if there's a change, and if so, write to disk
  setting_change = False
  # remote sees T/F whereas messageboard.py & the web interface expect 'on'/absent key
  if command['setting_screen_enabled_bool']:
    command['setting_screen_enabled'] = 'on'

  log_lines = []
  setting_keys = ['setting_screen_enabled', 'setting_max_distance', 'setting_max_altitude',
                  'setting_on_time', 'setting_off_time', 'setting_delay']
  for key in setting_keys:
    if command.get(key) != configuration.get(key):
      log_lines.append(' |-->Setting %s updated from %s to %s' % (
          key, str(configuration.get(key)), str(command[key])))
      setting_change = True
      configuration[key] = command[key]












  if setting_change:
    settings_string = messageboard.BuildSettings(configuration)
    to_parent_q.put(('update_configuration', (settings_string, )))

  # a command might request info about flight to be (re)displayed, irrespective of
  # whether the screen is on; if so, let's put that message at the front of the message
  # queue, and delete any subsequent messages in queue because presumably the button
  # was pushed either a) when the screen was off (so no messages in queue), or b)
  # because the screen was on, but the last flight details got lost after other screens!
  if command['last_plane']:
    to_parent_q.put(('replay', ()))
    log_lines.append(' |-->Requested last flight (re)display')

  # a command might request a histogram; simply generate and save a histogram file to disk
  if command['histogram_enabled']:
    h_type = GetName(HISTOGRAM_TYPES, command['current_hist_type'])
    h_history = GetName(HISTOGRAM_HISTORY, command['current_hist_history'])
    to_parent_q.put(('histogram', (h_type, h_history)))
    log_lines.append(' |-->Requested %s histogram with %s data' % (h_type, h_history))





                            <----SKIPPED LINES---->





def RemoteMain(to_arduino_q, to_parent_q, shutdown):
  """Main process for controlling the arduino-based remote control.

  Takes various data from the messageboard and formats it for display on the alphanumeric
  display on the remote control; provides latest configuration; and executes any commands
  such as histogram requests or setting updates.
  """
  sys.stderr = open(messageboard.STDERR_FILE, 'a')

  Log('Process started with process id %d' % os.getpid())

  # Ensures that the child can exit if the parent exits unexpectedly
  # docs.python.org/2/library/multiprocessing.html#multiprocessing.Queue.cancel_join_thread
  to_arduino_q.cancel_join_thread()
  to_parent_q.cancel_join_thread()

  #pylint: disable = bad-whitespace
  read_config = (
      # when confirmed is true, this is a command; when false, this is a heartbeat
      ('confirmed',              '?'),
      ('setting_screen_enabled', '?'),
      ('setting_max_distance',   'H'),
      ('setting_max_altitude',   'L'),
      ('setting_on_time',        'H'),
      ('setting_off_time',       'H'),
      ('setting_delay',          'H'),
      ('last_plane',             '?'),
      ('display_mode',           'H'),
      ('histogram_enabled',      '?'),
      ('current_hist_type',      'H'),
      ('current_hist_history',   'H'),
      ('low_battery',            '?'))

  write_config = (
      ('setting_screen_enabled', '?'),  # 1 bytes
      ('setting_max_distance',   'H'),  # 2 bytes
      ('setting_max_altitude',   'L'),  # 4 bytes
      ('setting_on_time',        'H'),  # 2 bytes
      ('setting_off_time',       'H'),  # 2 bytes
      ('setting_delay',          'H'),  # 2 bytes
      ('line1',                  '9s'), # 9 bytes; 8 character plus terminator
      ('line2',                  '9s'), # 9 bytes; 8 character plus terminator
      ('line1_dec_mask',         'H'),  # 2 bytes
      ('line2_dec_mask',         'H'),  # 2 bytes
      ('display_mode',           'H'),  # 2 bytes
  )
  #pylint: enable = bad-whitespace
  read_keys, unused_read_format_tuple, read_format_string = SplitFormat(read_config)
  write_keys, write_format_tuple, write_format_string = SplitFormat(write_config)

  values_d = {}
  low_batt = False
  to_parent_q.put(('pin', (messageboard.GPIO_ERROR_BATTERY_CHARGE, low_batt)))

  link = Serial(
      *REMOTE_CONNECTION, read_timeout=7,
      error_pin=messageboard.GPIO_ERROR_ARDUINO_REMOTE_CONNECTION, to_parent_q=to_parent_q,
      read_format=read_format_string, write_format=write_format_string, name='Remote')
  link.Open()

  # Read in the saved display mode, if it exists
  display_mode = messageboard.ReadFile(REMOTE_DISPLAY_MODE, log_exception=False)
  if not display_mode:
    display_mode = DISP_LAST_FLIGHT_NUMB_ORIG_DEST
  else:




                            <----SKIPPED LINES---->

                            <----SKIPPED LINES---->




  - (Re)display a recent flight
  - Display a histogram
  - Send information for a different display mode
  - Indicate that the battery is low

  Args:
    command: dictionary representing all data fields from remote.
    configuration: dictionary representing the current state of the messageboard
      configuration.
    display_mode: current display mode; only passed so that we may identify changes.
    low_battery: current battery status; only passed so that we may identify changes.
    to_parent_q: multiprocessing queue, where instructions to send back to messageboard,
      if any, can be placed.
    link: the open serial link.

  Returns:
    A 2-tuple of potentially-updated display_mode, and low_battery.
  """
  # command might update a setting; see if there's a change, and if so, write to disk
  setting_change = False




  log_lines = []
  setting_keys = ['setting_max_distance', 'setting_max_altitude',
                  'setting_on_time', 'setting_off_time', 'setting_delay']
  for key in setting_keys:
    if command.get(key) != configuration.get(key):
      log_lines.append(' |-->Setting %s updated from %s to %s' % (
          key, str(configuration.get(key)), str(command[key])))
      setting_change = True
      configuration[key] = command[key]
  remote_key = 'setting_screen_enabled_bool'
  system_key = 'setting_screen_enabled'
  # remote sees T/F whereas messageboard.py & the web interface expect 'on'/absent key
  if command[remote_key] and system_key not in configuration:
    setting_change = True
    configuration[system_key] = 'on'
    log_lines.append(' |-->Setting %s updated from None to on' % system_key)
  elif not command[remote_key] and system_key in configuration:
    setting_change = True
    configuration.pop(system_key)
    log_lines.append(' |-->Setting %s updated from on to None' % system_key)

  if setting_change:
    settings_string = messageboard.BuildSettings(configuration)
    to_parent_q.put(('update_configuration', (settings_string, )))

  # a command might request info about flight to be (re)displayed, irrespective of
  # whether the screen is on; if so, let's put that message at the front of the message
  # queue, and delete any subsequent messages in queue because presumably the button
  # was pushed either a) when the screen was off (so no messages in queue), or b)
  # because the screen was on, but the last flight details got lost after other screens!
  if command['last_plane']:
    to_parent_q.put(('replay', ()))
    log_lines.append(' |-->Requested last flight (re)display')

  # a command might request a histogram; simply generate and save a histogram file to disk
  if command['histogram_enabled']:
    h_type = GetName(HISTOGRAM_TYPES, command['current_hist_type'])
    h_history = GetName(HISTOGRAM_HISTORY, command['current_hist_history'])
    to_parent_q.put(('histogram', (h_type, h_history)))
    log_lines.append(' |-->Requested %s histogram with %s data' % (h_type, h_history))





                            <----SKIPPED LINES---->





def RemoteMain(to_arduino_q, to_parent_q, shutdown):
  """Main process for controlling the arduino-based remote control.

  Takes various data from the messageboard and formats it for display on the alphanumeric
  display on the remote control; provides latest configuration; and executes any commands
  such as histogram requests or setting updates.
  """
  sys.stderr = open(messageboard.STDERR_FILE, 'a')

  Log('Process started with process id %d' % os.getpid())

  # Ensures that the child can exit if the parent exits unexpectedly
  # docs.python.org/2/library/multiprocessing.html#multiprocessing.Queue.cancel_join_thread
  to_arduino_q.cancel_join_thread()
  to_parent_q.cancel_join_thread()

  #pylint: disable = bad-whitespace
  read_config = (
      # when confirmed is true, this is a command; when false, this is a heartbeat
      ('confirmed',                   '?'),
      ('setting_screen_enabled_bool', '?'),
      ('setting_max_distance',        'H'),
      ('setting_max_altitude',        'L'),
      ('setting_on_time',             'H'),
      ('setting_off_time',            'H'),
      ('setting_delay',               'H'),
      ('last_plane',                  '?'),
      ('display_mode',                'H'),
      ('histogram_enabled',           '?'),
      ('current_hist_type',           'H'),
      ('current_hist_history',        'H'),
      ('low_battery',                 '?'))

  write_config = (
      ('setting_screen_enabled',      '?'),  # 1 bytes
      ('setting_max_distance',        'H'),  # 2 bytes
      ('setting_max_altitude',        'L'),  # 4 bytes
      ('setting_on_time',             'H'),  # 2 bytes
      ('setting_off_time',            'H'),  # 2 bytes
      ('setting_delay',               'H'),  # 2 bytes
      ('line1',                       '9s'), # 9 bytes; 8 character plus terminator
      ('line2',                       '9s'), # 9 bytes; 8 character plus terminator
      ('line1_dec_mask',              'H'),  # 2 bytes
      ('line2_dec_mask',              'H'),  # 2 bytes
      ('display_mode',                'H'),  # 2 bytes
  )
  #pylint: enable = bad-whitespace
  read_keys, unused_read_format_tuple, read_format_string = SplitFormat(read_config)
  write_keys, write_format_tuple, write_format_string = SplitFormat(write_config)

  values_d = {}
  low_batt = False
  to_parent_q.put(('pin', (messageboard.GPIO_ERROR_BATTERY_CHARGE, low_batt)))

  link = Serial(
      *REMOTE_CONNECTION, read_timeout=7,
      error_pin=messageboard.GPIO_ERROR_ARDUINO_REMOTE_CONNECTION, to_parent_q=to_parent_q,
      read_format=read_format_string, write_format=write_format_string, name='Remote')
  link.Open()

  # Read in the saved display mode, if it exists
  display_mode = messageboard.ReadFile(REMOTE_DISPLAY_MODE, log_exception=False)
  if not display_mode:
    display_mode = DISP_LAST_FLIGHT_NUMB_ORIG_DEST
  else:




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