XRA00 datasheet(10/40 Pages) STMICROELECTRONICS

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XRA00

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Table 3. Request Modulation Pulse Parameters for European Operation (

−20 to 55°C)

Note: The data shown in Table 3. is Preliminary Data. It is subject to change without previous notice.

Request Frame Format

Readers communicate with the XRA00 using two

types of modulation: Data modulation and Bin

modulation.

Data modulation is used to transmit data from the

Reader to the XRA00.

Bin modulation is used to synchronize XRA00 an-

swers and define time slot intervals while running

the XRA00 anti-collision algorithm after a PINGID

command.

All transactions begin with a transaction gap pulse,

ttrangap, followed by a period of time at least equal

to ttransetup that precedes the Data modulation win-

dow as described in Figure 11.

During the Data modulation, the Reader provides

a master clock signal to XRA00 devices located in

its neighborhood. The time between clock pulses,

t0, determines the Reader-to-XRA00 data rate.

The XRA00 devices are synchronized to the

Reader on the negative-going edge of the low lev-

el interval of the RF envelope. There is a propor-

tional relationship between this fundamental

frequency and all subsequent signaling.

The encoding used for the binary data from the

Reader to the XRA00 is the pulse width modula-

tion of the low level pulse as shown in Figure 12.

Logical 0 is defined as a modulation whose width

is 1/8 of the master clock interval (Figure 6.), t0.

Logical 1 is encoded as a modulation whose width

is 3/8 of the master clock interval (Figure 7.), t0.

After the Data modulation windows in which the

Reader generates the XRA00 command, the

Reader generates Bin pulses to define the time

slots used by the XRA00 to answer. During the

first interval, after the Data modulation EOF, the

XRA00 sets up for answers. The XRA00 uses one

out of two Bin modulation schemes depending on

the Reader command.

For SCROLL commands, the Reader generates 1

Bin pulse used for synchronization, followed by the

XRA00 answer.

For PING commands, the Reader generates 8 BIN

pulses to define 8 BIN response windows. These

8 BIN response windows are used to delineate

XRA00 answers during a PINGID command.

A BIN interval is defined by a BIN pulse with a

width of tfwhmBin = 3/8t0, followed by a BIN re-

sponse window delay of tfwhmBinRW = 8T0.

Symbol

Description

Min

Max

Units

UHF Carrier Frequency

860

870

MHz

Master Clock Time Period for a single bit sent to the XRA00

66,67

µs

t0Tol

Master Clock Time Period Tolerance

-1

1/t0

Request Frame Data Rate (1/T0)

Kbps

tfwhm0

Pulse Modulation Width of Binary Data 0 at 50% Level

1/8 * T0

µs

tfwhm1

Pulse Modulation Width of Binary Data 1 at 50% Level

3/8 * T0

µs

tfwhmBin

Pulse Modulation Width of Bin Pulse at 50% Level

3/8 * T0

µs

ttrangap

Pulse Modulation Width of Transaction Gap at 50% Level

10/8 * T0

µs

tfwhmBinRW

Bin Response Window at 50% Level

4*T0

8*T0

µs

ttransetup

Delay between Transaction Gap and Data Modulation Windows

µs

ttranhold

Delay before the next Transaction Gap

2.5*T0

2000

µs

Pulse Modulation Fall Time (90% to 10% level)

300

Pulse Modulation Rise Time (10% to 90% level)

300

Ripple

MOD

Pulse Modulation Depth

tCoast

Delay between Request EOF and the next Transaction Gap

TReset

RF Off time to Power down a XRA00

200

µs

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