AN3955 datasheet(36/68 Pages) STMICROELECTRONICS

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ISO/IEC 14443-3 layers

AN3955

36/68

Doc ID 022017 Rev 1

The ISO14443_IsCorrectBCC function returns RESULTOK if the XOR of Data is equal to

BCC

. Otherwise, the ISO14443_IsCorrectBCC function returns ERRORCODE_GENERIC.

Table 50 describes the ISO14443A_IsCorrectBCC function.

Table 50.

ISO14443A_IsCorrectBCC function description

5.1.10

ISO/IEC 14443-3 Type A GET functions

The ISO14443A_GetSignificantBit function returns the number of significant bits of

the first byte. This information is extracted from the control bytes of the CR95HF response.

Table 51 describes the ISO14443A_GetSignificantBit function.

Table 51.

ISO14443A_GetSignificantBit function description

The ISO14443A_GetFirtsCollisionByte function returns the index of the first byte

where the collision is detected. This information is extracted from the control bytes of

CR95HF. Table 52 describes the ISO14443A_GetFirstCollisionByte function.

Table 52.

ISO14443A_GetFirstCollisionByte function description

Prototype

int8_t ISO14443A_IsCorrectBCC (uint8_t NbByte,

uint8_t*Data, uint8_t BCC);

Input parameter

NbByte: Number of bytes of Data

Data: Data to check (without BCC byte)

BCC: BCC byte of contactless tag response

Output parameter

None

Return parameter

RESULTOK: BCC byte is equal to the XOR of Data.

ERRORCODE_GENERIC: BCC byte is different to XOR of Data.

Prototype

int8_t ISO14443A_GetSignificantBit (uc8*CR95HF

ControlByteIndex);

Input parameter

CR95HFControlByteIndex: Pointer of the CR95HF control bytes (3

bytes)(1).

Three control bytes are appended by CR95HF to contactless tag response. Refer to Table 12: CR95HF

success response value for ISO/IEC 14443-3 Type A.

Output parameter

None

Return parameter

Number of significant bit of the first byte

Prototype

int8_t ISO14443A_GetFirstCollisionByte (uc8*CR95HF

ControlByteIndex);

Input parameter

CR95HFControlByteIndex: Pointer of the CR95HF control bytes (3

bytes)(1).

Three control bytes are appended by CR95HF to contactless tag response. Refer to Table 12: CR95HF

success response value for ISO/IEC 14443-3 Type A.

Output parameter

None

Return parameter

Index of the first byte where the collision is detected.

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