XRA00 datasheet(13/40 Pages) STMICROELECTRONICS

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XRA00

Output Data Transfer from the XRA00 to the

Reader

Answer Binary Data Bits 0 and 1. The

back-

scattered answer from the XRA00 is modulated by

a selection of one out of two symbols per data bit

cell. The data bit cell period ttagbitcell is defined as

2 transitions for a binary data 0, and 4 transitions

for a binary data 1 as shown in Figure 17. The

nominal data rate for the XRA00 answer is syn-

chronized to twice the Request data rate (defined

in Table 4.).

Under this encoding scheme, there are always

transitions in the middle of a data bit and the se-

quence of 0’s and 1’s remains unchanged when

the code is inverted as shown in Figure 19.

Figure 17. XRA00 Answer Binary Data Bit Cell Encoding

Answer Frame from the XRA00 to the Reader.

The XRA00 answers to Reader commands with a

backscatter modulation that follows the FSK bit

coding scheme as shown in Figure 17. This

scheme define two symbols which are binary data

0 and binary data 1, respectively.

After a Reader BIN pulse, the XRA00 waits for a

time that depends on the received command be-

ore starting to generate the answer. The XRA00

answer consists of an 8 bit Preamble followed by

the data bits read from the non-volatile memory.

The preamble has a fixed value of 11111110 and

is sent as shown in Figure 18. The data bits are

sent lowest bit address first.

Figure 18. XRA00 Answer Preamble

ttagbitcell = 1/2t0

ttagbitcell

Answer Data 1

Answer Data 0

ai10756

ttagscrollDel

EOF

READER

LSB MSB

TAG

11111110

CRC data

Preamble

(8 bits)

16 bits

Tag ID Code

96 bits

ai10757

Bin Pulse

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