LRI64 datasheet(18/52 Pages) STMICROELECTRONICS

18 / 52 page

Special fields

LRI64

18/52

10.2

Application family identifier (AFI)

The application family identifier (AFI) indicates the type of application targeted by the VCD,

and is used to select only those LRI64 devices meeting the required application criteria (as

summarized in Figure 14). The value is programmed by the LRI64 issuer in the AFI register.

Once programmed, it cannot be modified.

The most significant nibble of the AFI is used to indicate one specific application, or all

families. The least significant nibble of the AFI is used to code one specific subfamilies, or all

subfamilies. Subfamily codes, other than 0, are proprietary (as described in ISO 15693 and

ISO 18000-3 Mode 1 documentation).

10.3

Data storage format identifier (DSFID)

The data storage format identifier (DSFID) indicates how the data is structured in the LRI64

memory. It is coded on one byte. It allows for quick and brief knowledge on the logical

organization of the data. It is programmed by the LRI64 issuer in the DSFID register. Once

programmed, it cannot be modified.

10.4

Cyclic redundancy code (CRC)

The cyclic redundancy code (CRC) is calculated as defined in ISO/IEC 13239, starting from

an initial register content of all ones: FFFFh.

The 2-byte CRC is appended to each request and each response, within each frame, before

the EOF. The CRC is calculated on all the bytes after the SOF, up to the CRC field.

Upon reception of a request from the VCD, the LRI64 verifies that the CRC value is valid. If

it is invalid, it discards the frame, and does not answer the VCD.

Upon reception of a response from the LRI64, it is recommended that the VCD verify that

the CRC value is valid. If it is invalid, the actions that need to be performed are up to the

VCD designer.

The CRC is transmitted least significant byte first. Each byte is transmitted Least Significant

Bit first, as shown in Figure 15).

Figure 15.

CRC format

AI09726

Most Significant Byte

Least Significant Byte

l.s.bit

m.s.bit

LRI64 датащи(PDF) 18 Page - STMicroelectronics