Type 2 Tag parser¶
The nRF Connect SDK provides functionality to read the content of an NFC tag. Note that an nRF5 Series IC does not provide the hardware that is required for a polling device. If you want to create a polling device, you can use an ST25R3911B NFC shield together with an nRF5 Development Kit.
Using the NFC Reader ST25R3911B, you can read raw data from a Type 2 Tag, such as:
Number of TLV structures in the tag
Type 2 Tag internal bytes
Type 2 Tag lock bytes
Type 2 Tag capability container
Array of pointer to the TLV structures of the tag
See the NFC: Tag reader sample for more information on how to do this.
The following code example shows how to parse the raw data from a Type 2 Tag:
/* Buffer with raw data from a Type 2 Tag. */
uint8_t raw_tag_data[] = ..;
/* Declaration of Type 2 Tag structure which
* can contain a maximum of 10 TLV blocks.
*/
NFC_T2T_DESC_DEF(tag_data, 10);
struct nfc_t2t *t2t = &NFC_T2T_DESC(tag_data);
err = nfc_t2t_parse(t2t, raw_tag_data);
if (err) {
printk("Not enough memory to read the whole tag. Printing what has been read.\n");
}
/* Print the tag data. */
nfc_t2t_printout(t2t);
Note that the data can be further parsed by the Parser for messages and records, given that the type of the analyzed TLV block is NDEF TLV.
API documentation¶
NFC Type 2 Tag parser¶
include/nfc/t2t/t2t_parser.h
subsys/nfc/t2t/parser.c
-
group
nfc_t2t_parser
NFC Type 2 Tag parser.
Defines
-
NFC_T2T_DESC_DEF
(_name, _max_blocks)¶ Create and initialize a Type 2 Tag descriptor.
This macro creates and initializes a static instance of an nfc_t2t structure and an array of Type 2 Tag TLV blocks descriptors.
Use the macro NFC_T2T_DESC to access the Type 2 Tag descriptor instance.
- Parameters
_name – [in] Name of the created descriptor instance.
_max_blocks – [in] Maximum number of Type 2 Tag TLV blocks descriptors that can be stored in the array.
-
NFC_T2T_DESC
(_name)¶ Access the nfc_t2t instance that was created with NFC_T2T_DESC_DEF.
-
NFC_T2T_NFC_FORUM_DEFINED_DATA
¶ Value indicating that the Type 2 Tag contains NFC Forum defined data.
-
NFC_T2T_UID_BCC_CASCADE_BYTE
¶ Value used for calculating the first BCC byte of a Type 2 Tag serial number.
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NFC_T2T_SUPPORTED_MAJOR_VERSION
¶ Supported major version of the Type 2 Tag specification.
-
NFC_T2T_SUPPORTED_MINOR_VERSION
¶ Supported minor version of the Type 2 Tag specification.
-
NFC_T2T_BLOCK_SIZE
¶ Type 2 Tag block size in bytes.
-
NFC_T2T_CC_BLOCK_OFFSET
¶ Offset of the Capability Container area in the Type 2 Tag.
-
NFC_T2T_FIRST_DATA_BLOCK_OFFSET
¶ Offset of the data area in the Type 2 Tag.
Functions
-
void
nfc_t2t_clear
(struct nfc_t2t *t2t)¶ Clear the nfc_t2t structure.
- Parameters
t2t – [inout] Pointer to the structure that should be cleared.
-
int
nfc_t2t_parse
(struct nfc_t2t *t2t, const uint8_t *raw_data)¶ Parse raw data that was read from a Type 2 Tag.
This function parses the header and the following TLV blocks of a Type 2 Tag. The data is read from a buffer and stored in a nfc_t2t structure.
- Parameters
t2t – [out] Pointer to the structure that will be filled with parsed data.
raw_data – [in] Pointer to the buffer with raw data from the tag (should point at the first byte of the first block of the tag).
- Returns 0
If the operation was successful. Otherwise, a (negative) error code is returned.
-
struct
nfc_t2t_sn
¶ - #include <parser.h>
Descriptor for the internal bytes of a Type 2 Tag.
Public Members
-
uint8_t
manufacturer_id
¶ Manufacturer ID (the most significant byte of the UID/serial number).
-
uint16_t
serial_number_part_1
¶ Bytes 5-4 of the tag UID.
-
uint32_t
serial_number_part_2
¶ Bytes 3-0 of the tag UID.
-
uint8_t
check_byte_0
¶ First block check character byte (XOR of the cascade tag byte, manufacturer ID byte, and the serial_number_part_1 bytes).
-
uint8_t
check_byte_1
¶ Second block check character byte (XOR of the serial_number_part_2 bytes).
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uint8_t
internal
¶ Tag internal bytes.
-
uint8_t
-
struct
nfc_t2t_cc
¶ - #include <parser.h>
Descriptor for the Capability Container (CC) bytes of a Type 2 Tag.
Public Members
-
uint8_t
major_version
¶ Major version of the supported Type 2 Tag specification.
-
uint8_t
minor_version
¶ Minor version of the supported Type 2 Tag specification.
-
uint16_t
data_area_size
¶ Size of the data area in bytes.
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uint8_t
read_access
¶ Read access for the data area.
-
uint8_t
write_access
¶ Write access for the data area.
-
uint8_t
-
struct
nfc_t2t
¶ - #include <parser.h>
Type 2 Tag descriptor.
Public Members
-
struct nfc_t2t_sn
sn
¶ Values within the serial number area of the tag.
-
uint16_t
lock_bytes
¶ Value of the lock bytes.
-
struct nfc_t2t_cc
cc
¶ Values within the Capability Container area of the tag.
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const uint16_t
max_tlv_blocks
¶ Maximum number of TLV blocks that can be stored.
-
struct nfc_t2t_tlv_block *
tlv_block_array
¶ Pointer to the array for TLV blocks.
-
uint16_t
tlv_count
¶ Number of TLV blocks stored in the Type 2 Tag.
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struct nfc_t2t_sn
-
Type 2 Tag TLV blocks¶
include/nfc/t2t/tlv_block.h
-
group
nfc_t2t_tlv_block
Descriptor for a Type 2 Tag TLV block.
Defines
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NFC_T2T_TLV_T_LENGTH
¶ Length of a tag field.
-
NFC_T2T_TLV_L_SHORT_LENGTH
¶ Length of a short length field.
-
NFC_T2T_TLV_L_LONG_LENGTH
¶ Length of an extended length field.
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NFC_T2T_TLV_L_FORMAT_FLAG
¶ Value indicating the use of an extended length field.
-
NFC_T2T_TLV_NULL_TERMINATOR_LEN
¶ Predefined length of the NULL and TERMINATOR TLV blocks.
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NFC_T2T_TLV_LOCK_MEMORY_CTRL_LEN
¶ Predefined length of the LOCK CONTROL and MEMORY CONTROL blocks.
Enums
-
enum
nfc_t2t_tlv_block_types
¶ Tag field values.
Possible values for the tag field in a TLV block.
Values:
-
enumerator
NFC_T2T_TLV_NULL
¶ Can be used for padding of memory areas.
-
enumerator
NFC_T2T_TLV_LOCK_CONTROL
¶ Defines details of the lock bits.
-
enumerator
NFC_T2T_TLV_MEMORY_CONTROL
¶ Identifies reserved memory areas.
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enumerator
NFC_T2T_TLV_NDEF_MESSAGE
¶ Contains an NDEF message.
-
enumerator
NFC_T2T_TLV_PROPRIETARY
¶ Tag proprietary information.
-
enumerator
NFC_T2T_TLV_TERMINATOR
¶ Last TLV block in the data area.
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enumerator
-
struct
nfc_t2t_tlv_block
¶ - #include <tlv_block.h>
TLV block descriptor.
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