EM4450

EM4550

Copyright

 2003, EM Microelectronic-Marin SA

5

www.emmicroelectronic.com

Memory Organisation

The 1024 bit EEPROM is organised in 32 words of 32 bits. The first three words are assigned to the Password, the

Protection word, and the Control word. In order to write one of these three words, it is necessary to send the valid

password. At fabrication, the EM4450/4550 comes with all bits of the password programmed to a logic "0". The Password

cannot be read out. The memory contains two extra words of Laser ROM. These words are laser programmed during

fabrication for every chip, are unique and cannot be altered.

Memory Map

Bit 0

------------------------------

Bit 31

Word 0

PASSWORD

EE

Control Word

Protection Word

1

PROTECTION WORD

EE

0 – 7

First Word Read

0 – 7

First Word Read Protected

CONTROL WORD

EE

8 – 15

Last Word Read

8 – 15

Last Word Read Protected

3

EE

16

Password Check On/Off

16 – 23

First Word Write Inhibited

928 Bits of USER

17

Read After Write On/Off

24 – 31

Last Word Write Inhibited

EEPROM

18 – 31

User available

31

Password

32

DEVICE SERIAL NUMBER

Laser

Write Only – No Read Access

33

DEVICE IDENTIFICATION

Laser

On means bit set to logic '1'

Device Identification Word &

Off means bit set to logic '0'

Serial Number Word

Laser Programmed – Read only

Fig.5

Standard Read Mode

After a Power-On-Reset and upon completion of a command, the chip will execute the Standard Read Mode, in which it will

send data continuously, word by word from the memory section defined between the First Word Read (FWR) and Last

Word Read (LWR). When the last word is output, the chip will continue with the first word until the transceiver sends a

request. If FWR and LWR are the same, the same word will be sent repetitively. The Listen Window (LIW) is generated

before each word to check if the transceiver is sending data. The LIW has a duration of 320 (160 opt 32) periods of the RF

field. FWR and LWR have to be programmed as valid addresses (FWR

≤ LWR and ≤ 33).

The words sent by the EM4450/4550 comprise 32 data bits and parity bits. The parity bits are not stored in the EEPROM,

but generated while the message is sent as described below. The parity is even for rows and columns, meaning that the

total number of "1's" is even (including the parity bit).

Word organisation (Words 0 to 33)

Fig. 6

When a word is read protected, the output will consist of 45 bits set to logic "0". The password has to be used to output

correctly a read protected memory area.

D0

D1

D2

D3

D4

D5

D6

D7

P0

D8

D9

D10

D11

D12

D13

D14

D15

P1

D16

D17

D18

D19

D20

D21

D22

D23

P2

D24

D25

D26

D27

D28

D29

D30

D31

P3

PC0

PC1

PC2

PC3

PC4

PC5

PC6

PC7

0

First bit output

Data

Row Even Parity

Last bit output

logic '0'

Column Even Partiy