NAME

Tinkerforge::BrickletNFC - NFC tag read/write, NFC P2P and Card Emulation

CONSTANTS

DEVICE_IDENTIFIER

This constant is used to identify a NFC 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 Bricklet.

CALLBACK_READER_STATE_CHANGED

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

CALLBACK_CARDEMU_STATE_CHANGED

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

CALLBACK_P2P_STATE_CHANGED

This constant is used with the register_callback() subroutine to specify the CALLBACK_P2P_STATE_CHANGED callback.

FUNCTION_SET_MODE

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

FUNCTION_GET_MODE

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

FUNCTION_READER_REQUEST_TAG_ID

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

FUNCTION_READER_GET_TAG_ID_LOW_LEVEL

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

FUNCTION_READER_GET_STATE

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

FUNCTION_READER_WRITE_NDEF_LOW_LEVEL

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

FUNCTION_READER_REQUEST_NDEF

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

FUNCTION_READER_READ_NDEF_LOW_LEVEL

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

FUNCTION_READER_AUTHENTICATE_MIFARE_CLASSIC_PAGE

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

FUNCTION_READER_WRITE_PAGE_LOW_LEVEL

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

FUNCTION_READER_REQUEST_PAGE

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

FUNCTION_READER_READ_PAGE_LOW_LEVEL

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

FUNCTION_CARDEMU_GET_STATE

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

FUNCTION_CARDEMU_START_DISCOVERY

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

FUNCTION_CARDEMU_WRITE_NDEF_LOW_LEVEL

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

FUNCTION_CARDEMU_START_TRANSFER

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

FUNCTION_P2P_GET_STATE

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

FUNCTION_P2P_START_DISCOVERY

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

FUNCTION_P2P_WRITE_NDEF_LOW_LEVEL

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

FUNCTION_P2P_START_TRANSFER

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

FUNCTION_P2P_READ_NDEF_LOW_LEVEL

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

FUNCTION_SET_DETECTION_LED_CONFIG

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

FUNCTION_GET_DETECTION_LED_CONFIG

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

FUNCTION_GET_SPITFP_ERROR_COUNT

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

FUNCTION_SET_BOOTLOADER_MODE

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

FUNCTION_GET_BOOTLOADER_MODE

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

FUNCTION_SET_WRITE_FIRMWARE_POINTER

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

FUNCTION_WRITE_FIRMWARE

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

FUNCTION_SET_STATUS_LED_CONFIG

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

FUNCTION_GET_STATUS_LED_CONFIG

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

FUNCTION_GET_CHIP_TEMPERATURE

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

FUNCTION_RESET

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

FUNCTION_WRITE_UID

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

FUNCTION_READ_UID

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*.

set_mode()

Sets the mode. The NFC Bricklet supports four modes:

* Off * Card Emulation (Cardemu): Emulates a tag for other readers * Peer to Peer (P2P): Exchange data with other readers * Reader: Reads and writes tags

If you change a mode, the Bricklet will reconfigure the hardware for this mode. Therefore, you can only use functions corresponding to the current mode. For example, in Reader mode you can only use Reader functions.

The default mode is "off".

get_mode()

Returns the mode as set by :func:`Set Mode`.

reader_request_tag_id()

To read or write a tag that is in proximity of the NFC 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 answers the request.

Currently the following tag types are supported:

* Mifare Classic * NFC Forum Type 1 * NFC Forum Type 2 * NFC Forum Type 3 * NFC Forum Type 4

After you call :func:`Reader Request Tag ID` the NFC 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 :cb:`Reader State Changed` callback or you can poll :func:`Reader Get State` to find out about the state change.

If the state changes to *ReaderRequestTagIDError* it means that either there was no tag present or that the tag has an incompatible type. If the state changes to *ReaderRequestTagIDReady* it means that a compatible tag was found and that the tag ID has been saved. You can now read out the tag ID by calling :func:`Reader Get Tag ID`.

If two tags are in the proximity of the NFC Bricklet, this function will cycle through the tags. To select a specific tag you have to call :func:`Reader Request Tag ID` until the correct tag ID is found.

In case of any *ReaderError* state the selection is lost and you have to start again by calling :func:`Reader Request Tag ID`.

reader_get_tag_id_low_level()

Returns the tag type and the tag ID. This function can only be called if the NFC Bricklet is currently in one of the *ReaderReady* states. The returned tag ID is the tag ID that was saved through the last call of :func:`Reader Request Tag ID`.

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

1. Call :func:`Reader Request Tag ID` 2. Wait for state to change to *ReaderRequestTagIDReady* (see :func:`Reader Get State` or :cb:`Reader State Changed` callback) 3. Call :func:`Reader Get Tag ID`

reader_get_state()

Returns the current reader state of the NFC Bricklet.

On startup the Bricklet will be in the *ReaderInitialization* state. The initialization will only take about 20ms. After that it changes to *ReaderIdle*.

The Bricklet is also reinitialized if the mode is changed, see :func:`Set Mode`.

The functions of this Bricklet can be called in the *ReaderIdle* state and all of the *ReaderReady* and *ReaderError* states.

Example: If you call :func:`Reader Request Page`, the state will change to *ReaderRequestPage* until the reading of the page is finished. Then it will change to either *ReaderRequestPageReady* if it worked or to *ReaderRequestPageError* if it didn't. If the request worked you can get the page by calling :func:`Reader Read Page`.

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

reader_write_ndef_low_level()

Writes NDEF formated data with a maximum of 255 bytes.

This function currently supports NFC Forum Type 2 and 4.

The general approach for writing a NDEF message is as follows:

1. Call :func:`Reader Request Tag ID` 2. Wait for state to change to *ReaderRequestTagIDReady* (see :func:`Reader Get State` or :cb:`Reader State Changed` callback) 3. If looking for a specific tag then call :func:`Reader Get Tag ID` and check if the expected tag was found, if it was not found got back to step 1 4. Call :func:`Reader Write NDEF` with the NDEF message that you want to write 5. Wait for state to change to *ReaderWriteNDEFReady* (see :func:`Reader Get State` or :cb:`Reader State Changed` callback)

reader_request_ndef()

Reads NDEF formated data from a tag.

This function currently supports NFC Forum Type 1, 2, 3 and 4.

The general approach for reading a NDEF message is as follows:

1. Call :func:`Reader Request Tag ID` 2. Wait for state to change to *RequestTagIDReady* (see :func:`Reader Get State` or :cb:`Reader State Changed` callback) 3. If looking for a specific tag then call :func:`Reader Get Tag ID` and check if the expected tag was found, if it was not found got back to step 1 4. Call :func:`Reader Request NDEF` 5. Wait for state to change to *ReaderRequestNDEFReady* (see :func:`Reader Get State` or :cb:`Reader State Changed` callback) 6. Call :func:`Reader Read NDEF` to retrieve the NDEF message from the buffer

reader_read_ndef_low_level()

Returns the NDEF data from an internal buffer. To fill the buffer with a NDEF message you have to call :func:`Reader Request NDEF` beforehand.

The buffer can have a size of up to 8192 bytes.

reader_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 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:`Reader Request Tag ID` 2. Wait for state to change to *ReaderRequestTagIDReady* (see :func:`Reader Get State` or :cb:`Reader State Changed` callback) 3. If looking for a specific tag then call :func:`Reader Get Tag ID` and check if the expected tag was found, if it was not found got back to step 1 4. Call :func:`Reader Authenticate Mifare Classic Page` with page and key for the page 5. Wait for state to change to *ReaderAuthenticatingMifareClassicPageReady* (see :func:`Reader Get State` or :cb:`Reader State Changed` callback) 6. Call :func:`Reader Request Page` or :func:`Reader Write Page` to read/write page

The authentication will always work for one whole sector (4 pages).

reader_write_page_low_level()

Writes a maximum of 8192 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 * NFC Forum Type 1 page size: 8 byte * NFC Forum Type 2 page size: 4 byte * NFC Forum Type 3 page size: 16 byte * NFC Forum Type 4: No pages, page = file selection (CC or NDEF, see below)

The general approach for writing to a tag is as follows:

1. Call :func:`Reader Request Tag ID` 2. Wait for state to change to *ReaderRequestTagIDReady* (see :func:`Reader Get State` or :cb:`Reader State Changed` callback) 3. If looking for a specific tag then call :func:`Reader Get Tag ID` and check if the expected tag was found, if it was not found got back to step 1 4. Call :func:`Reader Write Page` with page number and data 5. Wait for state to change to *ReaderWritePageReady* (see :func:`Reader Get State` or :cb:`Reader State Changed` callback)

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

NFC Forum Type 4 tags are not organized into pages but different files. We currently support two files: Capability Container file (CC) and NDEF file.

Choose CC by setting page to 3 or NDEF by setting page to 4.

reader_request_page()

Reads a maximum of 8192 bytes starting from the given page and stores them into a buffer. The buffer can then be read out with :func:`Reader Read Page`. How many pages are read depends on the tag type. The page sizes are as follows:

* Mifare Classic page size: 16 byte * NFC Forum Type 1 page size: 8 byte * NFC Forum Type 2 page size: 4 byte * NFC Forum Type 3 page size: 16 byte * NFC Forum Type 4: No pages, page = file selection (CC or NDEF, see below)

The general approach for reading a tag is as follows:

1. Call :func:`Reader Request Tag ID` 2. Wait for state to change to *RequestTagIDReady* (see :func:`Reader Get State` or :cb:`Reader State Changed` callback) 3. If looking for a specific tag then call :func:`Reader Get Tag ID` and check if the expected tag was found, if it was not found got back to step 1 4. Call :func:`Reader Request Page` with page number 5. Wait for state to change to *ReaderRequestPageReady* (see :func:`Reader Get State` or :cb:`Reader State Changed` callback) 6. Call :func:`Reader Read 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 :func:`Reader Authenticate Mifare Classic Page`.

NFC Forum Type 4 tags are not organized into pages but different files. We currently support two files: Capability Container file (CC) and NDEF file.

Choose CC by setting page to 3 or NDEF by setting page to 4.

reader_read_page_low_level()

Returns the page data from an internal buffer. To fill the buffer with specific pages you have to call :func:`Reader Request Page` beforehand.

The buffer can have a size of up to 8192 bytes.

cardemu_get_state()

Returns the current cardemu state of the NFC Bricklet.

On startup the Bricklet will be in the *CardemuInitialization* state. The initialization will only take about 20ms. After that it changes to *CardemuIdle*.

The Bricklet is also reinitialized if the mode is changed, see :func:`Set Mode`.

The functions of this Bricklet can be called in the *CardemuIdle* state and all of the *CardemuReady* and *CardemuError* states.

Example: If you call :func:`Cardemu Start Discovery`, the state will change to *CardemuDiscover* until the discovery is finished. Then it will change to either *CardemuDiscoverReady* if it worked or to *CardemuDiscoverError* if it didn't.

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

cardemu_start_discovery()

Starts the discovery process. If you call this function while a NFC reader device is near to the NFC Bricklet the state will change from *CardemuDiscovery* to *CardemuDiscoveryReady*.

If no NFC reader device can be found or if there is an error during discovery the cardemu state will change to *CardemuDiscoveryError*. In this case you have to restart the discovery process.

If the cardemu state changes to *CardemuDiscoveryReady* you can start the NDEF message transfer with :func:`Cardemu Write NDEF` and :func:`Cardemu Start Transfer`.

cardemu_write_ndef_low_level()

Writes the NDEF messages that is to be transferred to the NFC peer.

The maximum supported NDEF message size in Cardemu mode is 255 byte.

You can call this function at any time in Cardemu mode. The internal buffer will not be overwritten until you call this function again or change the mode.

cardemu_start_transfer()

You can start the transfer of a NDEF message if the cardemu state is *CardemuDiscoveryReady*.

Before you call this function to start a write transfer, the NDEF message that is to be transferred has to be written via :func:`Cardemu Write NDEF` first.

After you call this function the state will change to *CardemuTransferNDEF*. It will change to *CardemuTransferNDEFReady* if the transfer was successful or *CardemuTransferNDEFError* if it wasn't.

p2p_get_state()

Returns the current P2P state of the NFC Bricklet.

On startup the Bricklet will be in the *P2PInitialization* state. The initialization will only take about 20ms. After that it changes to *P2PIdle*.

The Bricklet is also reinitialized if the mode is changed, see :func:`Set Mode`.

The functions of this Bricklet can be called in the *P2PIdle* state and all of the *P2PReady* and *P2PError* states.

Example: If you call :func:`P2P Start Discovery`, the state will change to *P2PDiscover* until the discovery is finished. Then it will change to either P2PDiscoverReady* if it worked or to *P2PDiscoverError* if it didn't.

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

p2p_start_discovery()

Starts the discovery process. If you call this function while another NFC P2P enabled device is near to the NFC Bricklet the state will change from *P2PDiscovery* to *P2PDiscoveryReady*.

If no NFC P2P enabled device can be found or if there is an error during discovery the P2P state will change to *P2PDiscoveryError*. In this case you have to restart the discovery process.

If the P2P state changes to *P2PDiscoveryReady* you can start the NDEF message transfer with :func:`P2P Start Transfer`.

p2p_write_ndef_low_level()

Writes the NDEF messages that is to be transferred to the NFC peer.

The maximum supported NDEF message size for P2P transfer is 255 byte.

You can call this function at any time in P2P mode. The internal buffer will not be overwritten until you call this function again, change the mode or use P2P to read an NDEF messages.

p2p_start_transfer()

You can start the transfer of a NDEF message if the P2P state is *P2PDiscoveryReady*.

Before you call this function to start a write transfer, the NDEF message that is to be transferred has to be written via :func:`P2P Write NDEF` first.

After you call this function the P2P state will change to *P2PTransferNDEF*. It will change to *P2PTransferNDEFReady* if the transfer was successfull or *P2PTransferNDEFError* if it wasn't.

If you started a write transfer you are now done. If you started a read transfer you can now use :func:`P2P Read NDEF` to read the NDEF message that was written by the NFC peer.

p2p_read_ndef_low_level()

Returns the NDEF message that was written by a NFC peer in NFC P2P mode. The maximum NDEF length is 8192 byte.

The NDEF message is ready if you called :func:`P2P Start Transfer` with a read transfer and the P2P state changed to *P2PTransferNDEFReady*.

set_detection_led_config()

Sets the detection LED configuration. By default the LED shows if a card/reader is detected.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is off.

get_detection_led_config()

Returns the configuration as set by :func:`Set Detection LED Config`

get_spitfp_error_count()

Returns the error count for the communication between Brick and Bricklet.

The errors are divided into

* ack checksum errors, * message checksum errors, * frameing errors and * overflow errors.

The errors counts are for errors that occur on the Bricklet side. All Bricks have a similar function that returns the errors on the Brick side.

set_bootloader_mode()

Sets the bootloader mode and returns the status after the requested mode change was instigated.

You can change from bootloader mode to firmware mode and vice versa. A change from bootloader mode to firmware mode will only take place if the entry function, device identifier und crc are present and correct.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

get_bootloader_mode()

Returns the current bootloader mode, see :func:`Set Bootloader Mode`.

set_write_firmware_pointer()

Sets the firmware pointer for :func:`Write Firmware`. The pointer has to be increased by chunks of size 64. The data is written to flash every 4 chunks (which equals to one page of size 256).

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

write_firmware()

Writes 64 Bytes of firmware at the position as written by :func:`Set Write Firmware Pointer` before. The firmware is written to flash every 4 chunks.

You can only write firmware in bootloader mode.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

set_status_led_config()

Sets the status LED configuration. By default the LED shows communication traffic between Brick and Bricklet, it flickers once for every 10 received data packets.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is will show heartbeat by default.

get_status_led_config()

Returns the configuration as set by :func:`Set Status LED Config`

get_chip_temperature()

Returns the temperature in °C as measured inside the microcontroller. The value returned is not the ambient temperature!

The temperature is only proportional to the real temperature and it has bad accuracy. Practically it is only useful as an indicator for temperature changes.

reset()

Calling this function will reset the Bricklet. All configurations will be lost.

After a reset you have to create new device objects, calling functions on the existing ones will result in undefined behavior!

write_uid()

Writes a new UID into flash. If you want to set a new UID you have to decode the Base58 encoded UID string into an integer first.

We recommend that you use Brick Viewer to change the UID.

read_uid()

Returns the current UID as an integer. Encode as Base58 to get the usual string version.

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|

reader_get_tag_id()

Returns the tag type and the tag ID. This function can only be called if the NFC Bricklet is currently in one of the *ReaderReady* states. The returned tag ID is the tag ID that was saved through the last call of :func:`Reader Request Tag ID`.

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

1. Call :func:`Reader Request Tag ID` 2. Wait for state to change to *ReaderRequestTagIDReady* (see :func:`Reader Get State` or :cb:`Reader State Changed` callback) 3. Call :func:`Reader Get Tag ID`

reader_write_ndef()

Writes NDEF formated data with a maximum of 255 bytes.

This function currently supports NFC Forum Type 2 and 4.

The general approach for writing a NDEF message is as follows:

1. Call :func:`Reader Request Tag ID` 2. Wait for state to change to *ReaderRequestTagIDReady* (see :func:`Reader Get State` or :cb:`Reader State Changed` callback) 3. If looking for a specific tag then call :func:`Reader Get Tag ID` and check if the expected tag was found, if it was not found got back to step 1 4. Call :func:`Reader Write NDEF` with the NDEF message that you want to write 5. Wait for state to change to *ReaderWriteNDEFReady* (see :func:`Reader Get State` or :cb:`Reader State Changed` callback)

reader_read_ndef()

Returns the NDEF data from an internal buffer. To fill the buffer with a NDEF message you have to call :func:`Reader Request NDEF` beforehand.

The buffer can have a size of up to 8192 bytes.

reader_write_page()

Writes a maximum of 8192 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 * NFC Forum Type 1 page size: 8 byte * NFC Forum Type 2 page size: 4 byte * NFC Forum Type 3 page size: 16 byte * NFC Forum Type 4: No pages, page = file selection (CC or NDEF, see below)

The general approach for writing to a tag is as follows:

1. Call :func:`Reader Request Tag ID` 2. Wait for state to change to *ReaderRequestTagIDReady* (see :func:`Reader Get State` or :cb:`Reader State Changed` callback) 3. If looking for a specific tag then call :func:`Reader Get Tag ID` and check if the expected tag was found, if it was not found got back to step 1 4. Call :func:`Reader Write Page` with page number and data 5. Wait for state to change to *ReaderWritePageReady* (see :func:`Reader Get State` or :cb:`Reader State Changed` callback)

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

NFC Forum Type 4 tags are not organized into pages but different files. We currently support two files: Capability Container file (CC) and NDEF file.

Choose CC by setting page to 3 or NDEF by setting page to 4.

reader_read_page()

Returns the page data from an internal buffer. To fill the buffer with specific pages you have to call :func:`Reader Request Page` beforehand.

The buffer can have a size of up to 8192 bytes.

cardemu_write_ndef()

Writes the NDEF messages that is to be transferred to the NFC peer.

The maximum supported NDEF message size in Cardemu mode is 255 byte.

You can call this function at any time in Cardemu mode. The internal buffer will not be overwritten until you call this function again or change the mode.

p2p_write_ndef()

Writes the NDEF messages that is to be transferred to the NFC peer.

The maximum supported NDEF message size for P2P transfer is 255 byte.

You can call this function at any time in P2P mode. The internal buffer will not be overwritten until you call this function again, change the mode or use P2P to read an NDEF messages.

p2p_read_ndef()

Returns the NDEF message that was written by a NFC peer in NFC P2P mode. The maximum NDEF length is 8192 byte.

The NDEF message is ready if you called :func:`P2P Start Transfer` with a read transfer and the P2P state changed to *P2PTransferNDEFReady*.