Module: XBee::Frame

Defined in:
lib/apimode/frame/frame.rb,
lib/apimode/frame/at_command.rb,
lib/apimode/frame/modem_status.rb,
lib/apimode/frame/receive_packet.rb,
lib/apimode/frame/transmit_status.rb,
lib/apimode/frame/transmit_request.rb,
lib/apimode/frame/at_command_response.rb,
lib/apimode/frame/explicit_rx_indicator.rb,
lib/apimode/frame/remote_command_request.rb,
lib/apimode/frame/remote_command_response.rb,
lib/apimode/frame/explicit_addressing_command.rb

Defined Under Namespace

Classes: ATCommand, ATCommandQueueParameterValue, ATCommandResponse, Base, ExplicitAddressingCommand, ExplicitRxIndicator, ModemStatus, ReceivePacket, ReceivedFrame, RemoteCommandRequest, RemoteCommandResponse, TransmitRequest, TransmitStatus

Class Method Summary collapse

Class Method Details

.checksum(data) ⇒ Object 



14
15
16
 
# File 'lib/apimode/frame/frame.rb', line 14

def Frame.checksum(data)
  0xFF - (data.unpack("C*").inject(0) { |sum, byte| (sum + byte) & 0xFF })
end

.new(source_io, api_mode = :API1) ⇒ Object 



18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
 
# File 'lib/apimode/frame/frame.rb', line 18

def Frame.new(source_io, api_mode = :API1)
  stray_bytes = []
  unless api_mode == :API1 or api_mode == :API2
    raise "XBee api_mode must be either :API1 (non-escaped) or :API2 (escaped, default)"
  end
  until (start_delimiter = source_io.readchar.unpack('H*').join.to_i(16)) == 0x7e
    #puts "Stray byte 0x%x" % start_delimiter
    print "DEBUG: #{start_delimiter} | " if $DEBUG
    stray_bytes << start_delimiter
  end
  if $VERBOSE
    puts "Got some stray bytes for ya: #{stray_bytes.map {|b| "0x%x" % b} .join(", ")}" unless stray_bytes.empty?
  end
  if(api_mode == :API1)
    header = source_io.read(3)
  elsif(api_mode == :API2)
    header = source_io.read(2).xb_unescape
  end
  print "Reading ... header after start byte: #{header.unpack("C*").join(", ")} | " if $DEBUG
  frame_remaining = frame_length = api_identifier = cmd_data = ""
  if api_mode == :API2
    if header.length == 2
      frame_length = header.unpack("n").first
    else
      read_extra_byte = source_io.readchar
      if(read_extra_byte == "\175")
        # We stumbled upon another escaped character, read another byte and unescape
        read_extra_byte += source_io.readchar
        read_extra_byte = read_extra_byte.xb_unescape
      else
        header += read_extra_byte
      end
      frame_length = header.unpack("n")
    end
    api_identifier = source_io.readchar
    if(api_identifier == "\175")
      api_identifier += source_io.readchar
      api_identifier = api_identifier.xb_unescape
    end
    api_identifier = api_identifier.unpack("C").first
  else
    frame_length, api_identifier = header.unpack("nC")
  end
  #### DEBUG ####
  if $DEBUG then
  print "Frame length: #{frame_length} | "
  print "Api Identifier: #{api_identifier} | "
  end
  #### DEBUG ####
  cmd_data_intended_length = frame_length - 1
  if api_mode == :API2
    while ((unescaped_length = cmd_data.xb_unescape.length) < cmd_data_intended_length)
      cmd_data += source_io.read(cmd_data_intended_length - unescaped_length)
    end
    data = api_identifier.chr + cmd_data.xb_unescape
  else
    while (cmd_data.length < cmd_data_intended_length)
      cmd_data += source_io.read(cmd_data_intended_length)
    end
    data = api_identifier.chr + cmd_data
  end
  sent_checksum = source_io.getc.unpack('H*').join.to_i(16)
  #### DEBUG ####
  if $DEBUG then
  print "Sent checksum: #{sent_checksum} | "
  print "Received checksum: #{Frame.checksum(data)} | "
  print "Payload: #{cmd_data.unpack("C*").join(", ")} | "
  end
  #### DEBUG ####
  unless sent_checksum == Frame.checksum(data)
    raise "Bad checksum - data discarded"
  end
  case data[0].unpack('H*')[0].to_i(16)
    when 0x8A
      ModemStatus.new(data)
    when 0x88
      ATCommandResponse.new(data)
    when 0x97
      RemoteCommandResponse.new(data)
    when 0x8B
      TransmitStatus.new(data)
    when 0x90
      ReceivePacket.new(data)
    when 0x91
      ExplicitRxIndicator.new(data)
    when 0x92
      IODataSampleRxIndicator.new(data)
    else
      ReceivedFrame.new(data)
  end
  rescue EOFError
    # No operation as we expect eventually something
end