AN3985 datasheet(32/105 Pages) STMICROELECTRONICS

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ISO/IEC 15693 layer

AN3985

32/105

Doc ID 022255 Rev 2

Table 42 describes the bit for Request flag if the inventory flag is set (inventory commands)

For more information, please refer to ISO/IEC 15693 specification or ISO/IEC 15693

STMicroelectronics product datasheet.

Request flags and CR95HF_ProtocolSelect functions

The CR95HF_ProtocolSelect function (see Chapter 4.2.3: Protocol selection structure)

selects the RF protocol and defines the CR95HF datarate and contactless tag response

format (single or double subcarrier). Once the protocol and the RF parameters are

configured, the CR95HF can decode only contactless tag responses of same format and

datarate.

The datarate and contactless tag response format are also defined in the request flag byte

of each ISO/IEC 15693 command. The user application must ensure that the data rate and

subcarrier flags match the CR95HF_ProtocolSelect function parameters. This check is

performed by the functions of the ISO/IEC 15693 layer. If the parameters do not match, the

functions are not executed and the corresponding commands are not sent to the CR95HF.

5.3.3

Command code and Data management

The command and data shall be managed by user application.

5.3.4

CRC16 management

The ISO/IEC 15693 specification defines a two bytes CRC. It is appended to ISO/IEC 15693

command in order to check the data transmission between CR95HF and a contactless tag.

Bit 0 of parameter (AppendCRC) of ProtocolSelect command allows to append CRC to all

RF commands. The ISO15693_ComputeParameterByte_ProtocolSelect function

computes the parameter byte for protocol select according to the parameter provided and

sets the append CRC bit.

This bit 0 has to be set because the function in ISO/IEC 15693 and products layers will not

manage the CRC command. And the contactless tag will not answer to RF command.

Table 42.

Bit for request flag with inventory flag reset

Bit

Value

Description

AFI

AFI field is not present.

AFI field is present.

Data rate

16 slots

1 slot

Option

RFU

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