SRIX4K

2/5

SUMMARY DESCRIPTION

The SRIX4K is a contactless memory, powered by

an externally transmitted radio wave. It contains a

4096-bit user EEPROM fabricated with STMicro-

electronics CMOS technology. The memory is or-

ganised as 128 blocks of 32 bits. The SRIX4K is

accessed via the 13.56MHz carrier. Incoming data

are demodulated and decoded from the received

Amplitude Shift Keying (ASK) modulation signal

and outgoing data are generated by load variation

using Bit Phase Shift Keying (BPSK) coding of a

847kHz sub-carrier. The received ASK wave is

10% modulated. The Data transfer rate between

the SRIX4K and the reader is 106Kbit/s in both re-

ception and emission modes.

The SRIX4K follows the ISO 14443 part 2 type B

recommendation for the radio-frequency power

and signal interface.

Figure 2. Logic Diagram

The SRIX4K targets short range applications

which need secure and re-usable products. The

SRIX4K includes an anti-collision mechanism that

allows it to detect and select tags present at the

same time within range of the reader. The anti-col-

lision is based on a probabilistic scanning method

using slot markers. The SRIX4K provides an anti-

clone function which allows its authentication. Us-

ing the STMicroelectronics single chip coupler,

CRX14, it is easy to design a reader with the au-

thentication capability and to build a system with a

high level of security.

Table 1. Signal Names

The SRIX4K contactless EEPROM can be ran-

domly read and write in block mode. Each block is

composed by 32 bits. It offers a set of 10 com-

mands:

s

READ_BLOCK

s

WRITE_BLOCK

s

INITIATE

s

PCALL16

s

SLOT_MARKER

s

SELECT

s

COMPLETION

s

RESET_TO_INVENTORY

s

AUTHENTICATE

s

GET_UID

The SRIX4K memory is organized in three areas,

as described in Figure 3. The first area is a reset-

table OTP (one time programmable) area in which

bits can only be switched from 1 to 0. Using a spe-

cial command, it is possible to erase all bits of this

area to 1. The second area provides two 32-bit bi-

nary counters which can only be decremented

from FFFFFFFFh to 00000000h, and gives a ca-

pacity of 4,294,967,296 units per counter. The last

area is the EEPROM memory. It is accessible by

block of 32 bits and includes an auto-erase cycle

during each WRITE_BLOCK command.

AI06829

AC1

SRIX4K

AC0

Power

Supply

Regulator

BPSK

Load

Modulator

ASK

Demodulator

4 Kbit

User

EEPROM

AC1

Antenna Coil

AC0

Antenna Coil