This is the description of the Ruby API bindings for the NFC/RFID Bricklet. General information and technical specifications for the NFC/RFID Bricklet are summarized in its hardware description.
An installation guide for the Ruby API bindings is part of their general description.
The example code below is Public Domain (CC0 1.0).
Download (example_scan_for_tags.rb)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 | #!/usr/bin/env ruby
# -*- ruby encoding: utf-8 -*-
require 'tinkerforge/ip_connection'
require 'tinkerforge/bricklet_nfc_rfid'
include Tinkerforge
HOST = 'localhost'
PORT = 4223
UID = 'hjw' # Change to your UID
ipcon = IPConnection.new # Create IP connection
nfc = BrickletNFCRFID.new UID, ipcon # Create device object
current_tag_type = 0
ipcon.connect HOST, PORT # Connect to brickd
# Don't use device before ipcon is connected
# Register state changed callback
nfc.register_callback(BrickletNFCRFID::CALLBACK_STATE_CHANGED) do |state, idle|
if idle
current_tag_type = (current_tag_type + 1) % 3
nfc.request_tag_id current_tag_type
end
if state == BrickletNFCRFID::STATE_REQUEST_TAG_ID_READY
tag_type, tid_length, tid = nfc.get_tag_id
puts "Found tag of type #{tag_type} with ID " +
"#{tid.take(tid_length).each.map { |b| b.to_s(16) }.join ' '}"
end
end
nfc.request_tag_id(BrickletNFCRFID::TAG_TYPE_MIFARE_CLASSIC)
puts 'Press key to exit'
$stdin.gets
ipcon.disconnect
|
Download (example_write_read_type2.rb)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 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 | #!/usr/bin/env ruby
# -*- ruby encoding: utf-8 -*-
require 'tinkerforge/ip_connection'
require 'tinkerforge/bricklet_nfc_rfid'
include Tinkerforge
HOST = 'localhost'
PORT = 4223
UID = 'hjw' # Change to your UID
ipcon = IPConnection.new # Create IP connection
nfc = BrickletNFCRFID.new UID, ipcon # Create device object
ipcon.connect HOST, PORT # Connect to brickd
# Don't use device before ipcon is connected
# Register state changed callback
nfc.register_callback(BrickletNFCRFID::CALLBACK_STATE_CHANGED) do |state, idle|
if state == BrickletNFCRFID::STATE_REQUEST_TAG_ID_READY
puts "Tag found"
# Write 16 byte to pages 5-8
data_write = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]
nfc.write_page 5, data_write
puts "Writing data..."
elsif state == BrickletNFCRFID::STATE_WRITE_PAGE_READY
# Request pages 5-8
nfc.request_page 5
puts "Requesting data..."
elsif state == BrickletNFCRFID::STATE_REQUEST_PAGE_READY
# Get and print pages
data = nfc.get_page
puts "Read data: #{data}"
elsif (state & (1 << 6)) == (1 << 6)
# All errors have bit 6 set
puts "Error: #{state}"
end
end
# Select NFC Forum Type 2 tag
nfc.request_tag_id(BrickletNFCRFID::TAG_TYPE_TYPE2)
puts 'Press key to exit'
$stdin.gets
ipcon.disconnect
|
All methods listed below are thread-safe.
Parameters: |
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Creates an object with the unique device ID uid:
nfc_rfid = BrickletNFCRFID.new 'YOUR_DEVICE_UID', ipcon
This object can then be used after the IP Connection is connected (see examples above).
Parameters: | tag_type -- int |
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To read or write a tag that is in proximity of the NFC/RFID Bricklet you first have to call this function with the expected tag type as parameter. It is no problem if you don't know the tag type. You can cycle through the available tag types until the tag gives an answer to the request.
Current the following tag types are supported:
After you call #request_tag_id the NFC/RFID Bricklet will try to read the tag ID from the tag. After this process is done the state will change. You can either register the ::CALLBACK_STATE_CHANGED callback or you can poll #get_state to find out about the state change.
If the state changes to RequestTagIDError it means that either there was no tag present or that the tag is of an incompatible type. If the state changes to RequestTagIDReady it means that a compatible tag was found and that the tag ID could be read out. You can now get the tag ID by calling #get_tag_id.
If two tags are in the proximity of the NFC/RFID Bricklet, this function will cycle through the tags. To select a specific tag you have to call #request_tag_id until the correct tag id is found.
In case of any Error state the selection is lost and you have to start again by calling #request_tag_id.
The following constants are available for this function:
Returns the tag type, tag ID and the length of the tag ID (4 or 7 bytes are possible length). This function can only be called if the NFC/RFID is currently in one of the Ready states. The returned ID is the ID that was saved through the last call of #request_tag_id.
To get the tag ID of a tag the approach is as follows:
The following constants are available for this function:
The returned array has the values tag_type, tid_length and tid.
Returns the current state of the NFC/RFID Bricklet.
On startup the Bricklet will be in the Initialization state. The initialization will only take about 20ms. After that it changes to Idle.
The functions of this Bricklet can be called in the Idle state and all of the Ready and Error states.
Example: If you call #request_page, the state will change to RequestPage until the reading of the page is finished. Then it will change to either RequestPageReady if it worked or to RequestPageError if it didn't. If the request worked you can get the page by calling #get_page.
The same approach is used analogously for the other API functions.
Possible states are:
The following constants are available for this function:
The returned array has the values state and idle.
Parameters: |
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Mifare Classic tags use authentication. If you want to read from or write to a Mifare Classic page you have to authenticate it beforehand. Each page can be authenticated with two keys: A (key_number = 0) and B (key_number = 1). A new Mifare Classic tag that has not yet been written to can can be accessed with key A and the default key [0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF].
The approach to read or write a Mifare Classic page is as follows:
The following constants are available for this function:
Parameters: |
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Writes 16 bytes starting from the given page. How many pages are written depends on the tag type. The page sizes are as follows:
The general approach for writing to a tag is as follows:
If you use a Mifare Classic tag you have to authenticate a page before you can write to it. See #authenticate_mifare_classic_page.
Parameters: | page -- int |
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Reads 16 bytes starting from the given page and stores them into a buffer. The buffer can then be read out with #get_page. How many pages are read depends on the tag type. The page sizes are as follows:
The general approach for reading a tag is as follows:
If you use a Mifare Classic tag you have to authenticate a page before you can read it. See #authenticate_mifare_classic_page.
Returns 16 bytes of data from an internal buffer. To fill the buffer with specific pages you have to call #request_page beforehand.
Returns the version of the API definition (major, minor, revision) implemented by this API bindings. This is neither the release version of this API bindings nor does it tell you anything about the represented Brick or Bricklet.
Parameters: | function_id -- int |
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Returns the response expected flag for the function specified by the function ID parameter. It is true if the function is expected to send a response, false otherwise.
For getter functions this is enabled by default and cannot be disabled, because those functions will always send a response. For callback configuration functions it is enabled by default too, but can be disabled by #set_response_expected. For setter functions it is disabled by default and can be enabled.
Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.
See #set_response_expected for the list of function ID constants available for this function.
Parameters: |
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Changes the response expected flag of the function specified by the function ID parameter. This flag can only be changed for setter (default value: false) and callback configuration functions (default value: true). For getter functions it is always enabled and callbacks it is always disabled.
Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.
The following function ID constants are available for this function:
Parameters: | response_expected -- bool |
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Changes the response expected flag for all setter and callback configuration functions of this device at once.
Returns the UID, the UID where the Bricklet is connected to, the position, the hardware and firmware version as well as the device identifier.
The position can be 'a', 'b', 'c' or 'd'.
The device identifier numbers can be found here. There is also a constant for the device identifier of this Bricklet.
The returned array has the values uid, connected_uid, position, hardware_version, firmware_version and device_identifier.
Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the #register_callback function of the device object. The first parameter is the callback ID and the second parameter is a block:
nfc_rfid.register_callback BrickletNFCRFID::CALLBACK_EXAMPLE, do |param|
puts "#{param}"
end
The available constants with inherent number and type of parameters are described below.
Note
Using callbacks for recurring events is always preferred compared to using getters. It will use less USB bandwidth and the latency will be a lot better, since there is no round trip time.
Parameters: |
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This callback is called if the state of the NFC/RFID Bricklet changes. See #get_state for more information about the possible states.
The following constants are available for this function:
This constant is used to identify a NFC/RFID Bricklet.
The #get_identity() function and the ::CALLBACK_ENUMERATE callback of the IP Connection have a device_identifier parameter to specify the Brick's or Bricklet's type.