Functions

nfc.c File Reference

NFC library implementation. More...

#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <nfc/nfc.h>
#include "chips.h"
#include "drivers.h"
#include <nfc/nfc-messages.h>

Go to the source code of this file.

Functions

void nfc_list_devices (nfc_device_desc_t pnddDevices[], size_t szDevices, size_t *pszDeviceFound)
 Probe for discoverable supported devices (ie. only available for some drivers).
nfc_device_tnfc_connect (nfc_device_desc_t *pndd)
 Connect to a NFC device.
void nfc_disconnect (nfc_device_t *pnd)
 Disconnect from a NFC device.
bool nfc_configure (nfc_device_t *pnd, const nfc_device_option_t dco, const bool bEnable)
 Configure advanced NFC device settings.
bool nfc_initiator_init (const nfc_device_t *pnd)
 Initialize NFC device as initiator (reader).
bool nfc_initiator_select_dep_target (const nfc_device_t *pnd, const nfc_modulation_t nmInitModulation, const byte_t *pbtPidData, const size_t szPidDataLen, const byte_t *pbtNFCID3i, const size_t szNFCID3iDataLen, const byte_t *pbtGbData, const size_t szGbDataLen, nfc_target_info_t *pnti)
 Select a target and request active or passive mode for DEP (Data Exchange Protocol).
bool nfc_initiator_select_tag (const nfc_device_t *pnd, const nfc_modulation_t nmInitModulation, const byte_t *pbtInitData, const size_t szInitDataLen, nfc_target_info_t *pnti)
 Select a passive or emulated tag.
bool nfc_initiator_deselect_tag (const nfc_device_t *pnd)
 Deselect a selected passive or emulated tag.
bool nfc_initiator_transceive_bits (const nfc_device_t *pnd, const byte_t *pbtTx, const size_t szTxBits, const byte_t *pbtTxPar, byte_t *pbtRx, size_t *pszRxBits, byte_t *pbtRxPar)
 Transceive raw bit-frames.
bool nfc_initiator_transceive_dep_bytes (const nfc_device_t *pnd, const byte_t *pbtTx, const size_t szTxLen, byte_t *pbtRx, size_t *pszRxLen)
 Transceive data.
bool nfc_initiator_transceive_bytes (const nfc_device_t *pnd, const byte_t *pbtTx, const size_t szTxLen, byte_t *pbtRx, size_t *pszRxLen)
 Transceive byte and APDU frames.
bool nfc_initiator_mifare_cmd (const nfc_device_t *pnd, const mifare_cmd mc, const uint8_t ui8Block, mifare_param *pmp)
 Execute a MIFARE Classic Command.
bool nfc_target_init (const nfc_device_t *pnd, byte_t *pbtRx, size_t *pszRxBits)
 Initialize NFC device as an emulated tag.
bool nfc_target_receive_bits (const nfc_device_t *pnd, byte_t *pbtRx, size_t *pszRxBits, byte_t *pbtRxPar)
 Receive bit-frames.
bool nfc_target_receive_dep_bytes (const nfc_device_t *pnd, byte_t *pbtRx, size_t *pszRxLen)
 Receive data.
bool nfc_target_receive_bytes (const nfc_device_t *pnd, byte_t *pbtRx, size_t *pszRxLen)
 Receive bytes and APDU frames.
bool nfc_target_send_bits (const nfc_device_t *pnd, const byte_t *pbtTx, const size_t szTxBits, const byte_t *pbtTxPar)
 Send raw bit-frames.
bool nfc_target_send_bytes (const nfc_device_t *pnd, const byte_t *pbtTx, const size_t szTxLen)
 Send bytes and APDU frames.
bool nfc_target_send_dep_bytes (const nfc_device_t *pnd, const byte_t *pbtTx, const size_t szTxLen)
 Send data.
const char * nfc_device_name (nfc_device_t *pnd)
 Returns the device name.
const char * nfc_version (void)
 Returns the library version.

Detailed Description

NFC library implementation.

Definition in file nfc.c.


Function Documentation

bool nfc_configure ( nfc_device_t pnd,
const nfc_device_option_t  dco,
const bool  bEnable 
)

Configure advanced NFC device settings.

Returns:
Returns true if action was successfully performed; otherwise returns false.
Parameters:
pnd nfc_device_t struct pointer that represent currently used device
ndo nfc_device_option_t struct that contains options to set to device
bEnable boolean

Configures parameters and registers that control for example timing, modulation, frame and error handling. There are different categories for configuring the PN53X chip features (handle, activate, infinite and accept). These are defined to organize future settings that will become available when they are needed.

Definition at line 244 of file nfc.c.

nfc_device_t* nfc_connect ( nfc_device_desc_t pndd  ) 

Connect to a NFC device.

Parameters:
pndd Device description if specific device is wanted, NULL otherwise
Returns:
Returns pointer to a nfc_device_t struct if successfull; otherwise returns NULL value.

If pndd is NULL, the first available NFC device is claimed by libnfc. It will automatically search the system using all available drivers to determine a device is free.

If pndd is passed then libnfc will try to claim the right device using information provided by this struct.

When it has successfully claimed a NFC device, memory is allocated to save the device information. It will return a pointer to a nfc_device_t struct. This pointer should be supplied by every next function of libnfc that should perform an action with this device.

Definition at line 134 of file nfc.c.

const char* nfc_device_name ( nfc_device_t pnd  ) 

Returns the device name.

Returns:
Returns a string with the device name ( MUST be freed with free() )

Definition at line 1014 of file nfc.c.

void nfc_disconnect ( nfc_device_t pnd  ) 

Disconnect from a NFC device.

Parameters:
pnd nfc_device_t struct pointer that represent currently used device

Initiator is disconnected and the device, including allocated nfc_device_t struct, is released.

Definition at line 223 of file nfc.c.

bool nfc_initiator_deselect_tag ( const nfc_device_t pnd  ) 

Deselect a selected passive or emulated tag.

Returns:
Returns true if action was successfully performed; otherwise returns false.
Parameters:
pnd nfc_device_t struct pointer that represent currently used device

After selecting and communicating with a passive tag, this function could be used to deactivate and release the tag. This is very useful when there are multiple tags available in the field. It is possible to use the nfc_initiator_select_tag() function to select the first available tag, test it for the available features and support, deselect it and skip to the next tag until the correct tag is found.

Definition at line 550 of file nfc.c.

bool nfc_initiator_init ( const nfc_device_t pnd  ) 

Initialize NFC device as initiator (reader).

Returns:
Returns true if action was successfully performed; otherwise returns false.
Parameters:
pnd nfc_device_t struct pointer that represent currently used device

The NFC device is configured to function as RFID reader. After initialization it can be used to communicate to passive RFID tags and active NFC devices. The reader will act as initiator to communicate peer 2 peer (NFCIP) to other active NFC devices.

Definition at line 318 of file nfc.c.

bool nfc_initiator_mifare_cmd ( const nfc_device_t pnd,
const mifare_cmd  mc,
const uint8_t  ui8Block,
mifare_param *  pmp 
)

Execute a MIFARE Classic Command.

Returns:
Returns true if action was successfully performed; otherwise returns false.
Parameters:
pmp Some commands need additional information. This information should be supplied in the mifare_param union.

The specified MIFARE command will be executed on the tag. There are different commands possible, they all require the destination block number.

Note:
There are three different types of information (Authenticate, Data and Value).

First an authentication must take place using Key A or B. It requires a 48 bit Key (6 bytes) and the UID. They are both used to initialize the internal cipher-state of the PN53X chip (http://libnfc.org/hardware/pn53x-chip). After a successful authentication it will be possible to execute other commands (e.g. Read/Write). The MIFARE Classic Specification (http://www.nxp.com/acrobat/other/identification/M001053_MF1ICS50_rev5_3.pdf) explains more about this process.

Definition at line 710 of file nfc.c.

bool nfc_initiator_select_dep_target ( const nfc_device_t pnd,
const nfc_modulation_t  nmInitModulation,
const byte_t *  pbtPidData,
const size_t  szPidDataLen,
const byte_t *  pbtNFCID3i,
const size_t  szNFCID3iDataLen,
const byte_t *  pbtGbData,
const size_t  szGbDataLen,
nfc_target_info_t pnti 
)

Select a target and request active or passive mode for DEP (Data Exchange Protocol).

Returns:
Returns true if action was successfully performed; otherwise returns false.
Parameters:
pnd nfc_device_t struct pointer that represent currently used device
im Desired modulation (NM_ACTIVE_DEP or NM_PASSIVE_DEP for active, respectively passive mode)
pbtPidData passive initiator data, 4 or 5 bytes long, (optional, only for NM_PASSIVE_DEP, can be NULL)
pbtNFCID3i the NFCID3, 10 bytes long, of the initiator (optional, can be NULL)
pbtGbData generic data of the initiator, max 48 bytes long, (optional, can be NULL)

The NFC device will try to find the available target. The standards (ISO18092 and ECMA-340) describe the modulation that can be used for reader to passive communications.

Note:
nfc_target_info_t_dep will be returned when the target was acquired successfully.

Definition at line 344 of file nfc.c.

bool nfc_initiator_select_tag ( const nfc_device_t pnd,
const nfc_modulation_t  nmInitModulation,
const byte_t *  pbtInitData,
const size_t  szInitDataLen,
nfc_target_info_t pnti 
)

Select a passive or emulated tag.

Returns:
Returns true if action was successfully performed; otherwise returns false.
Parameters:
pnd nfc_device_t struct pointer that represent currently used device
im Desired modulation
pbtInitData Optional initiator data used for Felica, ISO14443B, Topaz Polling or for ISO14443A selecting a specific UID.
szInitDataLen Length of initiator data pbtInitData.

The NFC device will try to find the available passive tags. Some NFC devices are capable to emulate passive tags. The standards (ISO18092 and ECMA-340) describe the modulation that can be used for reader to passive communications. The chip needs to know with what kind of tag it is dealing with, therefore the initial modulation and speed (106, 212 or 424 kbps) should be supplied.

Note:
For every initial modulation type there is a different collection of information returned (in nfc_target_info_t pointer pti) They all fit in the data-type which is called nfc_target_info_t. This is a union which contains the tag information that belongs to the according initial modulation type.

Definition at line 405 of file nfc.c.

bool nfc_initiator_transceive_bits ( const nfc_device_t pnd,
const byte_t *  pbtTx,
const size_t  szTxBits,
const byte_t *  pbtTxPar,
byte_t *  pbtRx,
size_t *  pszRxBits,
byte_t *  pbtRxPar 
)

Transceive raw bit-frames.

Returns:
Returns true if action was successfully performed; otherwise returns false.
Parameters:
pbtTx contains a byte array of the frame that needs to be transmitted.
szTxBits contains the length in bits.
Note:
For example the REQA (0x26) command (first anti-collision command of ISO14443-A) must be precise 7 bits long. This is not possible by using nfc_initiator_transceive_bytes(). With that function you can only communicate frames that consist of full bytes. When you send a full byte (8 bits + 1 parity) with the value of REQA (0x26), a tag will simply not respond. More information about this can be found in the anti-colision example.
Parameters:
pbtTxPar parameter contains a byte array of the corresponding parity bits needed to send per byte.
Note:
For example if you send the SELECT_ALL (0x93, 0x20) = [ 10010011, 00100000 ] command, you have to supply the following parity bytes (0x01, 0x00) to define the correct odd parity bits. This is only an example to explain how it works, if you just are sending two bytes with ISO14443-A compliant parity bits you better can use the nfc_initiator_transceive_bytes() function.
Returns:
The received response from the tag will be stored in the parameters (pbtRx, pszRxBits and pbtRxPar). They work the same way as the corresponding parameters for transmission.

The NFC reader will transmit low-level messages where only the modulation is handled by the PN53X chip. Construction of the frame (data, CRC and parity) is completely done by libnfc. This can be very useful for testing purposes. Some protocols (e.g. MIFARE Classic) require to violate the ISO14443-A standard by sending incorrect parity and CRC bytes. Using this feature you are able to simulate these frames.

Definition at line 568 of file nfc.c.

bool nfc_initiator_transceive_bytes ( const nfc_device_t pnd,
const byte_t *  pbtTx,
const size_t  szTxLen,
byte_t *  pbtRx,
size_t *  pszRxLen 
)

Transceive byte and APDU frames.

Returns:
Returns true if action was successfully performed; otherwise returns false.

The reader will transmit the supplied bytes in pbtTx to the target (tag). It waits for the response and stores the received bytes in the pbtRx byte array. The parity bits are handled by the PN53X chip. The CRC can be generated automatically or handled manually. Using this function, frames can be communicated very fast via the NFC reader to the tag. Tests show that on average this way of communicating is much faster than using the regular driver/middle-ware (often supplied by manufacturers).

Warning:
The configuration option NDO_HANDLE_PARITY must be set to true (the default value).

Definition at line 670 of file nfc.c.

bool nfc_initiator_transceive_dep_bytes ( const nfc_device_t pnd,
const byte_t *  pbtTx,
const size_t  szTxLen,
byte_t *  pbtRx,
size_t *  pszRxLen 
)

Transceive data.

Returns:
Returns true if action was successfully performed; otherwise returns false.

The reader will transmit the supplied (data) bytes in pbtTx to the target (tag). It waits for the response and stores the received bytes in the pbtRx byte array. The difference between this function and nfc_initiator_transceive_bytes is that here pbtTx and pbtRx contain *only* the data sent and received and not any additional commands, that is all handled internally by the PN53X.

Definition at line 632 of file nfc.c.

void nfc_list_devices ( nfc_device_desc_t  pnddDevices[],
size_t  szDevices,
size_t *  pszDeviceFound 
)

Probe for discoverable supported devices (ie. only available for some drivers).

Parameters:
pnddDevices Array of nfc_device_desc_t previously allocated by the caller.
szDevices size of the pnddDevices array.
pszDeviceFound number of devices found.

Definition at line 96 of file nfc.c.

bool nfc_target_init ( const nfc_device_t pnd,
byte_t *  pbtRx,
size_t *  pszRxBits 
)

Initialize NFC device as an emulated tag.

Returns:
Returns true if action was successfully performed; otherwise returns false.

This functionality allows the NFC device to act as an emulated tag. There seems to be quite some options available for this feature. Not all of the PN53X modulations are tested and documented at the moment. At the moment it could best be seen as a preliminary functionality.

Warning:
Be aware that this function will wait (hang) until a command is received that is not part of the anti-collision. The RATS command for example would wake up the emulator. After this is received, the send and receive functions can be used.

Definition at line 778 of file nfc.c.

bool nfc_target_receive_bits ( const nfc_device_t pnd,
byte_t *  pbtRx,
size_t *  pszRxBits,
byte_t *  pbtRxPar 
)

Receive bit-frames.

Returns:
Returns true if action was successfully performed; otherwise returns false.

This function makes it possible to receive (raw) bit-frames. It returns all the messages that are stored in the FIFO buffer of the PN53X chip. It does not require to send any frame and thereby could be used to snoop frames that are transmitted by a nearby reader. Check out the NDO_ACCEPT_MULTIPLE_FRAMES configuration option to avoid losing transmitted frames.

Definition at line 837 of file nfc.c.

bool nfc_target_receive_bytes ( const nfc_device_t pnd,
byte_t *  pbtRx,
size_t *  pszRxLen 
)

Receive bytes and APDU frames.

Returns:
Returns true if action was successfully performed; otherwise returns false.

The main receive function that returns the received frames from a nearby reader.

Definition at line 899 of file nfc.c.

bool nfc_target_receive_dep_bytes ( const nfc_device_t pnd,
byte_t *  pbtRx,
size_t *  pszRxLen 
)

Receive data.

Returns:
Returns true if action was successfully performed; otherwise returns false.

The main receive function that returns the received data from a nearby reader. The difference between this function and nfc_target_receive_bytes is that here pbtRx contains *only* the data received and not any additional commands, that is all handled internally by the PN53X.

Definition at line 875 of file nfc.c.

bool nfc_target_send_bits ( const nfc_device_t pnd,
const byte_t *  pbtTx,
const size_t  szTxBits,
const byte_t *  pbtTxPar 
)

Send raw bit-frames.

Returns:
Returns true if action was successfully performed; otherwise returns false.

This function can be used to transmit (raw) bit-frames to the reader.

Definition at line 923 of file nfc.c.

bool nfc_target_send_bytes ( const nfc_device_t pnd,
const byte_t *  pbtTx,
const size_t  szTxLen 
)

Send bytes and APDU frames.

Returns:
Returns true if action was successfully performed; otherwise returns false.

To communicate byte frames and APDU responses to the reader, this function could be used.

Definition at line 966 of file nfc.c.

bool nfc_target_send_dep_bytes ( const nfc_device_t pnd,
const byte_t *  pbtTx,
const size_t  szTxLen 
)

Send data.

Returns:
Returns true if action was successfully performed; otherwise returns false.

To communicate data to the reader, this function could be used. The difference between this function and nfc_target_send_bytes is that here pbtTx contains *only* the data sent and not any additional commands, that is all handled internally by the PN53X.

Definition at line 990 of file nfc.c.

const char* nfc_version ( void   ) 

Returns the library version.

Returns:
Returns a string with the library version

Definition at line 1025 of file nfc.c.