NAME

Tinkerforge::BrickletNFCRFID - Reads and writes NFC and RFID tags

CONSTANTS

DEVICE_IDENTIFIER

This constant is used to identify a NFC/RFID Bricklet.

The get_identity() subroutine and the CALLBACK_ENUMERATE callback of the IP Connection have a device_identifier parameter to specify the Brick's or Bricklet's type.

DEVICE_DISPLAY_NAME

This constant represents the display name of a NFC/RFID Bricklet.

CALLBACK_STATE_CHANGED

This constant is used with the register_callback() subroutine to specify the CALLBACK_STATE_CHANGED callback.

FUNCTION_REQUEST_TAG_ID

This constant is used with the get_response_expected(), set_response_expected() and set_response_expected_all() subroutines.

FUNCTION_GET_TAG_ID

This constant is used with the get_response_expected(), set_response_expected() and set_response_expected_all() subroutines.

FUNCTION_GET_STATE

This constant is used with the get_response_expected(), set_response_expected() and set_response_expected_all() subroutines.

FUNCTION_AUTHENTICATE_MIFARE_CLASSIC_PAGE

This constant is used with the get_response_expected(), set_response_expected() and set_response_expected_all() subroutines.

FUNCTION_WRITE_PAGE

This constant is used with the get_response_expected(), set_response_expected() and set_response_expected_all() subroutines.

FUNCTION_REQUEST_PAGE

This constant is used with the get_response_expected(), set_response_expected() and set_response_expected_all() subroutines.

FUNCTION_GET_PAGE

This constant is used with the get_response_expected(), set_response_expected() and set_response_expected_all() subroutines.

FUNCTION_GET_IDENTITY

This constant is used with the get_response_expected(), set_response_expected() and set_response_expected_all() subroutines.

FUNCTIONS

new()

Creates an object with the unique device ID *uid* and adds it to the IP Connection *ipcon*.

request_tag_id()

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:

* Mifare Classic (``tag_type`` = 0) * NFC Forum Type 1 (``tag_type`` = 1) * NFC Forum Type 2 (``tag_type`` = 2)

After you call :func:`RequestTagID` 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 :func:`StateChanged` callback or you can poll :func:`GetState` 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 :func:`GetTagID`.

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 :func:`RequestTagID` 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 :func:`RequestTagID`.

get_tag_id()

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 :func:`RequestTagID`.

To get the tag ID of a tag the approach is as follows:

1. Call :func:`RequestTagID` 2. Wait for state to change to *RequestTagIDReady* (see :func:`GetState` or :func:`StateChanged`) 3. Call :func:`GetTagID`

get_state()

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 :func:`RequestPage`, 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 :func:`GetPage`.

The same approach is used analogously for the other API functions.

Possible states are:

* Initialization = 0 * Idle = 128 * Error = 192 * RequestTagID = 2 * RequestTagIDReady = 130 * RequestTagIDError = 194 * AuthenticatingMifareClassicPage = 3 * AuthenticatingMifareClassicPageReady = 131 * AuthenticatingMifareClassicPageError = 195 * WritePage = 4 * WritePageReady = 132 * WritePageError = 196 * RequestPage = 5 * RequestPageReady = 133 * RequestPageError = 197

authenticate_mifare_classic_page()

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:

1. Call :func:`RequestTagID` 2. Wait for state to change to *RequestTagIDReady* (see :func:`GetState` or :func:`StateChanged`) 3. If looking for a specific tag then call :func:`GetTagID` and check if the expected tag was found, if it was not found got back to step 1 4. Call :func:`AuthenticateMifareClassicPage` with page and key for the page 5. Wait for state to change to *AuthenticatingMifareClassicPageReady* (see :func:`GetState` or :func:`StateChanged`) 6. Call :func:`RequestPage` or :func:`WritePage` to read/write page

write_page()

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:

1. Call :func:`RequestTagID` 2. Wait for state to change to *RequestTagIDReady* (see :func:`GetState` or :func:`StateChanged`) 3. If looking for a specific tag then call :func:`GetTagID` and check if the expected tag was found, if it was not found got back to step 1 4. Call :func:`WritePage` with page number and data 5. Wait for state to change to *WritePageReady* (see :func:`GetState` or :func:`StateChanged`)

If you use a Mifare Classic tag you have to authenticate a page before you can write to it. See :func:`AuthenticateMifareClassicPage`.

request_page()

Reads 16 bytes starting from the given page and stores them into a buffer. The buffer can then be read out with :func:`GetPage`. 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:

1. Call :func:`RequestTagID` 2. Wait for state to change to *RequestTagIDReady* (see :func:`GetState` or :func:`StateChanged`) 3. If looking for a specific tag then call :func:`GetTagID` and check if the expected tag was found, if it was not found got back to step 1 4. Call :func:`RequestPage` with page number 5. Wait for state to change to *RequestPageReady* (see :func:`GetState` or :func:`StateChanged`) 6. Call :func:`GetPage` 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 :func:`AuthenticateMifareClassicPage`.

get_page()

Returns 16 bytes of data from an internal buffer. To fill the buffer with specific pages you have to call :func:`RequestPage` beforehand.

get_identity()

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 :ref:`here <device_identifier>`. |device_identifier_constant|