SRIX4K datasheet(9/50 Pages) STMICROELECTRONICS

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SRIX4K

Data transfer

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Data transfer

3.1

Input data transfer from the Reader to the SRIX4K (request

frame)

The reader must generate a 13.56 MHz sinusoidal carrier frequency at its antenna, with

enough energy to “remote-power” the memory. The energy received at the SRIX4K’s

antenna is transformed into a supply voltage by a regulator, and into data bits by the ASK

demodulator. For the SRIX4K to decode correctly the information it receives, the reader

must 10% amplitude-modulate the 13.56 MHz wave before sending it to the SRIX4K. This is

represented in Figure 3. The data transfer rate is 106 Kbits/s.

Figure 3.

10% ASK modulation of the received wave

3.1.1

Character transmission format for request frame

The SRIX4K transmits and receives data bytes as 10-bit characters, with the least

significant bit (b0) transmitted first, as shown in Figure 4. Each bit duration, an ETU

(Elementary Time Unit), is equal to 9.44 µs (1/106 kHz).

These characters, framed by a Start Of Frame (SOF) and an End Of Frame (EOF), are put

together to form a Command Frame as shown in Figure 10. A frame includes an SOF,

commands, addresses, data, a CRC and an EOF as defined in the ISO 14443-3 Type B

Standard. If an error is detected during data transfer, the SRIX4K does not execute the

command, but it does not generate an error frame.

Figure 4.

SRIX4K request frame character format

DATA BIT TO TRANSMIT

TO THE

10% ASK MODULATION

OF THE 13.56MHz WAVE,

GENERATED BY THE READER

Transfer time for one data bit is 1/106 kHz

SRIX4K

AI05729

ai07664

1 ETU

Start

"0"

Stop

"1"

MSb

LSb

Information Byte

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