EM4450 Datasheet, PDF (5/16 Pages) EM Microelectronic - MARIN SA – 1 KBit Read/Write Contactless Identification Device

EM4450
EM4550
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
Word 0
1
3
31
32
33
Bit 0 ------------------------------
PASSWORD
PROTECTION WORD
CONTROL WORD
928 Bits of USER
EEPROM
DEVICE SERIAL NUMBER
DEVICE IDENTIFICATION
Bit 31
EE
EE
EE
EE
Laser
Laser
Control Word
0–7
First Word Read
8 – 15 Last Word Read
16
Password Check On/Off
17
Read After Write On/Off
18 – 31 User available
On means bit set to logic '1'
Off means bit set to logic '0'
Protection Word
0–7
First Word Read Protected
8 – 15
Last Word Read Protected
16 – 23 First Word Write Inhibited
24 – 31 Last Word Write Inhibited
Password
Write Only – No Read Access
Device Identification Word &
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)
First bit output
Data
Row Even Parity
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
Column Even Partiy
Last bit output
logic '0'
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.
Copyright  2003, EM Microelectronic-Marin SA
5
www.emmicroelectronic.com