This is the description of the TCP/IP protocol for the NFC/RFID Bricklet. General information and technical specifications for the NFC/RFID Bricklet are summarized in its hardware description.
A general description of the TCP/IP protocol structure can be found here.
Function ID: | 1 |
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Request: |
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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.
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.
Function ID: | 2 |
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Request: | empty payload |
Response: |
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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:
Function ID: | 3 |
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Request: | empty payload |
Response: |
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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:
Function ID: | 4 |
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Request: |
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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 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:
Function ID: | 5 |
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Request: |
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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:
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.
Function ID: | 6 |
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Request: |
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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:
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.
Function ID: | 7 |
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Request: | empty payload |
Response: |
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Returns 16 bytes of data from an internal buffer. To fill the buffer with specific pages you have to call request_page beforehand.
Function ID: | 255 |
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Request: | empty payload |
Response: |
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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.