AT88SC0808CRF 데이터 시트보기 (PDF) - Atmel Corporation

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AT88SC0808CRF

CryptoRF™ EEPROM Memory 8 Kbits

Atmel Corporation 

Anticollision Protocol When the PICC enters the 13.56 Mhz RF field of the host reader (PCD), it performs a

power on reset (POR) function and waits silently for a valid Type B polling command.

The CryptoRF PICC processes the antitearing registers as part of the POR process.

The PCD initiates the anticollision process by issuing an REQB or WUPB command.

The WUPB command activates any card (PICC) in the field with a matching AFI code.

The REQB command performs the same function but does not affect a PICC in the halt

state. The REQB and WUPB commands contain an integer N indicating the number of

slots assigned to the anticollision process. The CryptoRF command set is available only

after the anticollision process has been completed.

CRC Error Detection

A two-byte CRC_B is required in each frame transmitted by the PICC or PCD to permit

transmission error detection. The CRC_B is calculated on all of the command and data

bytes in the frame. For encrypted data, the encryption is performed prior to CRC_B

calculation. The SOF, EOF, start bits, stop bits, and EGT are not included in the CRC_B

calculation. The two-byte CRC_B follows the data bytes in the frame.

Figure 2. Location of the Two CRC_B Bytes within a Frame

SOF

K data bytes

CRC1 CRC2

EOF

Type A Tolerance

The CRC polynomial is defined in ISO/IEC 14443 and ISO/IEC 13239 as x16 + x12 + x5 +

x0. This is a hex polynomial of $1021. The initial value of the register used for the

CRC_B calculation is all ones ($FFFF). When receiving information from the reader, the

PICC computes the CRC on the incoming command, data, and CRC bytes. After the

last bit has been processed, the CRC register should contain $0000.

The RF Interface is designed for use in multiprotocol applications. It will not latch or lock

up if exposed to Type A signals and will not respond to them. The PICC may reset in the

presence of Type A field modulation but is not damaged by exposure to Type A signals.

4 AT88SC0808CRF

5027AS–CRRF–05/03

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