class Tinkerforge::BrickletNFCRFID
Reads and writes NFC and RFID tags
Constants
- CALLBACK_STATE_CHANGED
This callback is called if the state of the NFC/RFID Bricklet changes. See
BrickletNFCRFID#get_state
for more information about the possible states.
Public Class Methods
Creates an object with the unique device ID uid
and adds it to the IP Connection ipcon
.
# File lib/tinkerforge/bricklet_nfc_rfid.rb, line 55 def initialize(uid, ipcon) super uid, ipcon, DEVICE_IDENTIFIER, DEVICE_DISPLAY_NAME @api_version = [2, 0, 0] @response_expected[FUNCTION_REQUEST_TAG_ID] = RESPONSE_EXPECTED_FALSE @response_expected[FUNCTION_GET_TAG_ID] = RESPONSE_EXPECTED_ALWAYS_TRUE @response_expected[FUNCTION_GET_STATE] = RESPONSE_EXPECTED_ALWAYS_TRUE @response_expected[FUNCTION_AUTHENTICATE_MIFARE_CLASSIC_PAGE] = RESPONSE_EXPECTED_FALSE @response_expected[FUNCTION_WRITE_PAGE] = RESPONSE_EXPECTED_FALSE @response_expected[FUNCTION_REQUEST_PAGE] = RESPONSE_EXPECTED_FALSE @response_expected[FUNCTION_GET_PAGE] = RESPONSE_EXPECTED_ALWAYS_TRUE @response_expected[FUNCTION_GET_IDENTITY] = RESPONSE_EXPECTED_ALWAYS_TRUE @callback_formats[CALLBACK_STATE_CHANGED] = [10, 'C ?'] @ipcon.add_device self end
Public Instance Methods
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 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:
-
Wait for state to change to RequestTagIDReady (see
BrickletNFCRFID#get_state
orCALLBACK_STATE_CHANGED
callback) -
If looking for a specific tag then call
BrickletNFCRFID#get_tag_id
and check if the expected tag was found, if it was not found go back to step 1 -
Call
BrickletNFCRFID#authenticate_mifare_classic_page
with page and key for the page -
Wait for state to change to AuthenticatingMifareClassicPageReady (see
BrickletNFCRFID#get_state
orCALLBACK_STATE_CHANGED
callback) -
Call
BrickletNFCRFID#request_page
orBrickletNFCRFID#write_page
to read/write page
# File lib/tinkerforge/bricklet_nfc_rfid.rb, line 163 def authenticate_mifare_classic_page(page, key_number, key) check_validity send_request FUNCTION_AUTHENTICATE_MIFARE_CLASSIC_PAGE, [page, key_number, key], 'S C C6', 8, '' end
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', 'd', 'e', 'f', 'g' or 'h' (Bricklet Port). A Bricklet connected to an :ref:`Isolator Bricklet <isolator_bricklet>` is always at position 'z'.
The device identifier numbers can be found :ref:`here <device_identifier>`. |device_identifier_constant|
# File lib/tinkerforge/bricklet_nfc_rfid.rb, line 242 def get_identity send_request FUNCTION_GET_IDENTITY, [], '', 33, 'Z8 Z8 k C3 C3 S' end
Returns 16 bytes of data from an internal buffer. To fill the buffer with specific pages you have to call BrickletNFCRFID#request_page
beforehand.
# File lib/tinkerforge/bricklet_nfc_rfid.rb, line 226 def get_page check_validity send_request FUNCTION_GET_PAGE, [], '', 24, 'C16' end
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 BrickletNFCRFID#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 BrickletNFCRFID#get_page
.
The same approach is used analogously for the other API functions.
# File lib/tinkerforge/bricklet_nfc_rfid.rb, line 139 def get_state check_validity send_request FUNCTION_GET_STATE, [], '', 10, 'C ?' end
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 BrickletNFCRFID#request_tag_id
.
To get the tag ID of a tag the approach is as follows:
-
Wait for state to change to RequestTagIDReady (see
BrickletNFCRFID#get_state
orCALLBACK_STATE_CHANGED
callback)
# File lib/tinkerforge/bricklet_nfc_rfid.rb, line 119 def get_tag_id check_validity send_request FUNCTION_GET_TAG_ID, [], '', 17, 'C C C7' end
Registers a callback with ID id
to the block block
.
# File lib/tinkerforge/bricklet_nfc_rfid.rb, line 247 def register_callback(id, &block) callback = block @registered_callbacks[id] = callback end
Reads 16 bytes starting from the given page and stores them into a buffer. The buffer can then be read out with BrickletNFCRFID#get_page
. How many pages are read depends on the tag type. The page sizes are as follows:
-
Mifare Classic page size: 16 byte (one page is read)
-
NFC Forum Type 1 page size: 8 byte (two pages are read)
-
NFC Forum Type 2 page size: 4 byte (four pages are read)
The general approach for reading a tag is as follows:
-
Wait for state to change to RequestTagIDReady (see
BrickletNFCRFID#get_state
orCALLBACK_STATE_CHANGED
callback) -
If looking for a specific tag then call
BrickletNFCRFID#get_tag_id
and check if the expected tag was found, if it was not found got back to step 1 -
Call
BrickletNFCRFID#request_page
with page number -
Wait for state to change to RequestPageReady (see
BrickletNFCRFID#get_state
orCALLBACK_STATE_CHANGED
callback) -
Call
BrickletNFCRFID#get_page
to retrieve the page from the buffer
If you use a Mifare Classic tag you have to authenticate a page before you can read it. See BrickletNFCRFID#authenticate_mifare_classic_page
.
# File lib/tinkerforge/bricklet_nfc_rfid.rb, line 218 def request_page(page) check_validity send_request FUNCTION_REQUEST_PAGE, [page], 'S', 8, '' end
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.
Currently the following tag types are supported:
-
Mifare Classic
-
NFC Forum Type 1
-
NFC Forum Type 2
After you call BrickletNFCRFID#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 BrickletNFCRFID#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 BrickletNFCRFID#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 BrickletNFCRFID#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 BrickletNFCRFID#request_tag_id
.
# File lib/tinkerforge/bricklet_nfc_rfid.rb, line 102 def request_tag_id(tag_type) check_validity send_request FUNCTION_REQUEST_TAG_ID, [tag_type], 'C', 8, '' end
Writes 16 bytes starting from the given page. How many pages are written depends on the tag type. The page sizes are as follows:
-
Mifare Classic page size: 16 byte (one page is written)
-
NFC Forum Type 1 page size: 8 byte (two pages are written)
-
NFC Forum Type 2 page size: 4 byte (four pages are written)
The general approach for writing to a tag is as follows:
-
Wait for state to change to RequestTagIDReady (see
BrickletNFCRFID#get_state
orCALLBACK_STATE_CHANGED
callback) -
If looking for a specific tag then call
BrickletNFCRFID#get_tag_id
and check if the expected tag was found, if it was not found got back to step 1 -
Call
BrickletNFCRFID#write_page
with page number and data -
Wait for state to change to WritePageReady (see
BrickletNFCRFID#get_state
orCALLBACK_STATE_CHANGED
callback)
If you use a Mifare Classic tag you have to authenticate a page before you can write to it. See BrickletNFCRFID#authenticate_mifare_classic_page
.
# File lib/tinkerforge/bricklet_nfc_rfid.rb, line 189 def write_page(page, data) check_validity send_request FUNCTION_WRITE_PAGE, [page, data], 'S C16', 8, '' end