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CRX14

The CRX14 is organized in four blocks:

– The I²C bus controller handles the serial con-

nection with the application host. It is compliant

with the 400kHz I²C bus specification and it con-

trols the read/write access to all the CRX14 reg-

isters.

– The RAM buffer is bi-directional. It stores all the

request frame bytes to be transmitted to the tag

and all received bytes send by the tag on the an-

swer frame.

– The transmitter powers all the contactless tags,

within range, by generating a RF magnetic field

at 13.56MHz on an external antenna. The field

is 10% modulated using ASK (amplitude shift

keying) modulation for outgoing data.

– The receiver demodulates the signal generated

on the antenna by the load variation of the con-

tactless tag. The resulting signal is decoded by

a 847KHz BPSK (binary phase shift keying)

sub-carrier decoder.

The CRX14 is designed to be connected to a dig-

ital host (Microcontroller or ASIC) which has to

manage all the communication protocol in both

transmit and receive mode through the I²C serial

bus.

CRX14 DEVICE OPERATION

The CRX14 chip coupler provides four volatile reg-

isters. They control all the behaviour of the device

and are described in Table 2.

Table 2. CRX14 Control Registers

PART NUMBERING

For a list of available options (speed, package,

etc.) or for further information on any aspect of this

device, please contact your nearest ST Sales Of-

fice.

Table 3. Ordering Information Scheme

I2C Address

Access

Purpose

00h

Parameters register

W

Set parameter register

R

Read parameter register

01h

Input/Output frame register

W

Store and send request frame to the tag.

Store tag answer frame

R

Transfer register content to Host

02h

Authenticate register

W

Start the Authenticate process

R

Get the Authenticate status

03h

Slot Marker register

W

Launch the automated anti-collision process

R

Not Applicable. Return data FFh.

Example:

CRX14

–MQ

/

XX

Device Type

CRX14

Package

MQ = SO16 (150 mil width)

Customer Code

XX = Given by the issuer