Modbus - NFC/RFID Bricklet¶

Basic Functions¶

BrickletNFCRFID.request_tag_id¶

Function ID:	1
Request:	tag_type – Type: uint8, Range: See meanings
Response:	no response

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 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 meanings are defined for the elements of this function:

For tag_type:

• 0 = Mifare Classic
• 1 = Type1
• 2 = Type2

BrickletNFCRFID.get_tag_id¶

Function ID:	2
Request:	empty payload
Response:	tag_type – Type: uint8, Range: See meanings tid_length – Type: uint8, Range: [4, 7] tid – Type: uint8[7], Range: [0 to 255]

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:

1. Call request_tag_id
2. Wait for state to change to RequestTagIDReady (see get_state or CALLBACK_STATE_CHANGED callback)
3. Call get_tag_id

The following meanings are defined for the elements of this function:

For tag_type:

• 0 = Mifare Classic
• 1 = Type1
• 2 = Type2

BrickletNFCRFID.get_state¶

Function ID:	3
Request:	empty payload
Response:	state – Type: uint8, Range: See meanings idle – Type: bool

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.

The following meanings are defined for the elements of this function:

For state:

• 0 = Initialization
• 128 = Idle
• 192 = Error
• 2 = Request Tag ID
• 130 = Request Tag ID Ready
• 194 = Request Tag ID Error
• 3 = Authenticating Mifare Classic Page
• 131 = Authenticating Mifare Classic Page Ready
• 195 = Authenticating Mifare Classic Page Error
• 4 = Write Page
• 132 = Write Page Ready
• 196 = Write Page Error
• 5 = Request Page
• 133 = Request Page Ready
• 197 = Request Page Error

BrickletNFCRFID.authenticate_mifare_classic_page¶

Function ID:	4
Request:	page – Type: uint16, Range: [0 to 216 - 1] key_number – Type: uint8, Range: See meanings key – Type: uint8[6], Range: [0 to 255]
Response:	no response

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 request_tag_id
2. Wait for state to change to RequestTagIDReady (see get_state or CALLBACK_STATE_CHANGED callback)
3. If looking for a specific tag then call get_tag_id and check if the expected tag was found, if it was not found go back to step 1
4. Call authenticate_mifare_classic_page with page and key for the page
5. Wait for state to change to AuthenticatingMifareClassicPageReady (see get_state or CALLBACK_STATE_CHANGED callback)
6. Call request_page or write_page to read/write page

The following meanings are defined for the elements of this function:

For key_number:

• 0 = A
• 1 = B

BrickletNFCRFID.write_page¶

Function ID:	5
Request:	page – Type: uint16, Range: [0 to 216 - 1] data – Type: uint8[16], Range: [0 to 255]
Response:	no response

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 request_tag_id
2. Wait for state to change to RequestTagIDReady (see get_state or CALLBACK_STATE_CHANGED callback)
3. If looking for a specific tag then call get_tag_id and check if the expected tag was found, if it was not found got back to step 1
4. Call write_page with page number and data
5. Wait for state to change to WritePageReady (see get_state or CALLBACK_STATE_CHANGED callback)

If you use a Mifare Classic tag you have to authenticate a page before you can write to it. See authenticate_mifare_classic_page.

BrickletNFCRFID.request_page¶

Function ID:	6
Request:	page – Type: uint16, Range: [0 to 216 - 1]
Response:	no response

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:

• 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 request_tag_id
2. Wait for state to change to RequestTagIDReady (see get_state or CALLBACK_STATE_CHANGED callback)
3. If looking for a specific tag then call get_tag_id and check if the expected tag was found, if it was not found got back to step 1
4. Call request_page with page number
5. Wait for state to change to RequestPageReady (see get_state or CALLBACK_STATE_CHANGED callback)
6. Call 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 authenticate_mifare_classic_page.

BrickletNFCRFID.get_page¶

Function ID:	7
Request:	empty payload
Response:	data – Type: uint8[16], Range: [0 to 255]

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

Advanced Functions¶

BrickletNFCRFID.get_identity¶

Function ID:	255
Request:	empty payload
Response:	uid – Type: char[8] connected_uid – Type: char[8] position – Type: char, Range: ['a' to 'h', 'z'] hardware_version – Type: uint8[3] 0: major – Type: uint8, Range: [0 to 255] 1: minor – Type: uint8, Range: [0 to 255] 2: revision – Type: uint8, Range: [0 to 255] firmware_version – Type: uint8[3] 0: major – Type: uint8, Range: [0 to 255] 1: minor – Type: uint8, Range: [0 to 255] 2: revision – Type: uint8, Range: [0 to 255] device_identifier – Type: uint16, Range: [0 to 216 - 1]

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 Isolator Bricklet is always at position 'z'.

The device identifier numbers can be found here. 

Callbacks¶

BrickletNFCRFID.CALLBACK_STATE_CHANGED¶

Function ID:	8
Response:	state – Type: uint8, Range: See meanings idle – Type: bool

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 meanings are defined for the elements of this function:

For state:

• 0 = Initialization
• 128 = Idle
• 192 = Error
• 2 = Request Tag ID
• 130 = Request Tag ID Ready
• 194 = Request Tag ID Error
• 3 = Authenticating Mifare Classic Page
• 131 = Authenticating Mifare Classic Page Ready
• 195 = Authenticating Mifare Classic Page Error
• 4 = Write Page
• 132 = Write Page Ready
• 196 = Write Page Error
• 5 = Request Page
• 133 = Request Page Ready
• 197 = Request Page Error