Shell - NFC/RFID Bricklet – Tinkerforge

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# Shell - NFC/RFID Bricklet

This is the description of the Shell API bindings for the NFC/RFID Bricklet. General information and technical specifications for the NFC/RFID Bricklet are summarized in its hardware description.

An installation guide for the Shell API bindings is part of their general description.

## Examples

The example code below is Public Domain (CC0 1.0).

### Scan For Tags

Download (example-scan-for-tags.sh)

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    #!/bin/sh
    # connects to localhost:4223 by default, use --host and --port to change it

    # change to your UID
    uid=hjw

    echo "0" > /tmp/tf_sft_tt

    # handle incoming state changed callbacks
    tinkerforge dispatch nfc-rfid-bricklet $uid state-changed\
     --execute "if [ {idle} ]
                then
                  tt=\`cat /tmp/tf_sft_tt\`
                  if [ \$tt -eq 0 ]
                    then tt=1
                  elif [ \$tt -eq 1 ]
                    then tt=2
                  elif [ \$tt -eq 2 ]
                    then tt=0
                  fi
                  echo \"\$tt\" > /tmp/tf_sft_tt
                  tinkerforge call nfc-rfid-bricklet $uid request-tag-id \$tt
                fi;
                if [ {state} -eq 130 ]
                  then tinkerforge call nfc-rfid-bricklet $uid get-tag-id
                fi" &

    tinkerforge call nfc-rfid-bricklet $uid request-tag-id 0

## API

Possible exit codes for all `tinkerforge` commands are:

- 1: interrupted (ctrl+c)
- 2: syntax error
- 21: Python 2.5 or newer is required
- 22: Python `argparse` module is missing
- 23: socket error
- 24: other exception
- 25: invalid placeholder in format string
- 26: authentication error
- 201: timeout occurred
- 209: invalid argument value
- 210: function is not supported
- 211: unknown error

### Command Structure

The common options of the `call` and `dispatch` commands are documented here. The specific command structure is shown below.

tinkerforge `call` `nfc-rfid-bricklet` [<option>..] <uid> <function> [<argument>..]

  Parameters:

  - <uid> -- string
  - <function> -- string

  The `call` command is used to call a function of the NFC/RFID Bricklet. It can take several options:

  - `--help` shows help for the specific `call` command and exits
  - `--list-functions` shows a list of known functions of the NFC/RFID Bricklet and exits

tinkerforge `dispatch` `nfc-rfid-bricklet` [<option>..] <uid> <callback>

  Parameters:

  - <uid> -- string
  - <callback> -- string

  The `dispatch` command is used to dispatch a callback of the NFC/RFID Bricklet. It can take several options:

  - `--help` shows help for the specific `dispatch` command and exits
  - `--list-callbacks` shows a list of known callbacks of the NFC/RFID Bricklet and exits

tinkerforge call `nfc-rfid-bricklet` <uid> `<function>` [<option>..] [<argument>..]

  Parameters:

  - <uid> -- string
  - <function> -- string

  The `<function>` to be called can take different options depending of its kind. All functions can take the following options:

  - `--help` shows help for the specific function and exits

  Getter functions can take the following options:

  - `--execute <command>` shell command line to execute for each incoming response (see section about output formatting for details)

  Setter functions can take the following options:

  - `--expect-response` requests response and waits for it

  The `--expect-response` option for setter functions allows to detect timeouts and other error conditions calls of setters as well. The device will then send a response for this purpose. If this option is not given for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

tinkerforge dispatch `nfc-rfid-bricklet` <uid> `<callback>` [<option>..]

  Parameters:

  - <uid> -- string
  - <callback> -- string

  The `<callback>` to be dispatched can take several options:

  - `--help` shows help for the specific callback and exits
  - `--execute <command>` shell command line to execute for each incoming response (see section about output formatting for details)

### Basic Functions

tinkerforge call `nfc-rfid-bricklet` <uid> `request-tag-id` <tag-type>

  Parameters:

  - <tag-type> -- int (has symbols)

  Output: | no output

  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 `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 `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 symbols are available for this function:

  - `mifare-classic` = 0, for <tag-type>
  - `type1` = 1, for <tag-type>
  - `type2` = 2, for <tag-type>

tinkerforge call `nfc-rfid-bricklet` <uid> `get-tag-id`

  Output:

  - tag-type -- int (has symbols)
  - tid-length -- int
  - tid -- int,int,int,int,int,int,int

  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 `state-changed`)
  3. Call `get-tag-id`

  The following symbols are available for this function:

  - `mifare-classic` = 0, for tag-type
  - `type1` = 1, for tag-type
  - `type2` = 2, for tag-type

tinkerforge call `nfc-rfid-bricklet` <uid> `get-state`

  Output:

  - state -- int (has symbols)
  - idle -- 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.

  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

  The following symbols are available for this function:

  - `initialization` = 0, for state
  - `idle` = 128, for state
  - `error` = 192, for state
  - `request-tag-id` = 2, for state
  - `request-tag-id-ready` = 130, for state
  - `request-tag-id-error` = 194, for state
  - `authenticating-mifare-classic-page` = 3, for state
  - `authenticating-mifare-classic-page-ready` = 131, for state
  - `authenticating-mifare-classic-page-error` = 195, for state
  - `write-page` = 4, for state
  - `write-page-ready` = 132, for state
  - `write-page-error` = 196, for state
  - `request-page` = 5, for state
  - `request-page-ready` = 133, for state
  - `request-page-error` = 197, for state

tinkerforge call `nfc-rfid-bricklet` <uid> `authenticate-mifare-classic-page` <page> <key-number> <key>

  Parameters:

  - <page> -- int
  - <key-number> -- int (has symbols)
  - <key> -- int,int,int,int,int,int

  Output: | no output

  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 `request-tag-id`
  2. Wait for state to change to RequestTagIDReady (see `get-state` or `state-changed`)
  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 `authenticate-mifare-classic-page` with page and key for the page
  5. Wait for state to change to AuthenticatingMifareClassicPageReady (see `get-state` or `state-changed`)
  6. Call `request-page` or `write-page` to read/write page

  The following symbols are available for this function:

  - `a` = 0, for <key-number>
  - `b` = 1, for <key-number>

tinkerforge call `nfc-rfid-bricklet` <uid> `write-page` <page> <data>

  Parameters:

  - <page> -- int
  - <data> -- int,int,int,int,int,int,int,int,int,int,int,int,int,int,int,int

  Output: | no output

  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 `state-changed`)
  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 `state-changed`)

  If you use a Mifare Classic tag you have to authenticate a page before you can write to it. See `authenticate-mifare-classic-page`.

tinkerforge call `nfc-rfid-bricklet` <uid> `request-page` <page>

  Parameters:

  - <page> -- int

  Output: | no output

  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 `state-changed`)
  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 `state-changed`)
  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`.

tinkerforge call `nfc-rfid-bricklet` <uid> `get-page`

  Output:

  - data -- int,int,int,int,int,int,int,int,int,int,int,int,int,int,int,int

  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

tinkerforge call `nfc-rfid-bricklet` <uid> `get-identity`

  Output:

  - uid -- string
  - connected-uid -- string
  - position -- char
  - hardware-version -- int,int,int
  - firmware-version -- int,int,int
  - device-identifier -- int (has symbols)

  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.

### Callbacks

Callbacks can be used to receive time critical or recurring data from the device:

    tinkerforge dispatch nfc-rfid-bricklet <uid> example

The available callbacks are described below.

Note

Using callbacks for recurring events is always preferred compared to using getters. It will use less USB bandwidth and the latency will be a lot better, since there is no round trip time.

tinkerforge dispatch `nfc-rfid-bricklet` <uid> `state-changed`

  Output:

  - state -- int (has symbols)
  - idle -- 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 symbols are available for this function:

  - `initialization` = 0, for state
  - `idle` = 128, for state
  - `error` = 192, for state
  - `request-tag-id` = 2, for state
  - `request-tag-id-ready` = 130, for state
  - `request-tag-id-error` = 194, for state
  - `authenticating-mifare-classic-page` = 3, for state
  - `authenticating-mifare-classic-page-ready` = 131, for state
  - `authenticating-mifare-classic-page-error` = 195, for state
  - `write-page` = 4, for state
  - `write-page-ready` = 132, for state
  - `write-page-error` = 196, for state
  - `request-page` = 5, for state
  - `request-page-ready` = 133, for state
  - `request-page-error` = 197, for state

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