I•CODE1 Chip Specification

Rev. 2.1

May 2000

SL040521.doc/M

Public

Page 7 of 22

5.3 Memory Organisation

The 512 bit EEPROM memory is divided into 16 blocks. A block is the smallest access unit. Each

block consists of 4 bytes (1 block = 32 bits). Bit 0 in each byte represents the least significant bit

(LSB) and bit 7 the most significant bit (MSB), respectively.

Byte 0

Byte 1

Byte 2

Byte 3

Block 0

SNR0

SNR1

SNR2

SNR3

Serial Number (lower bytes)

Block 1

SNR4

SNR5

SNR6

SNR7

Serial Number (higher bytes)

Block 2

F0

FF

FF

FF

Write Access Conditions

Block 3

x

x

x

x

Special Functions (EAS/QUIET)

Block 4

x

x

x

x

Family Code/Application Identifier/User Data

Block 5

x

x

x

x

User Data

Block 6

x

x

x

x

:

Block 7

x

x

x

x

:

Block 8

x

x

x

x

:

Block 9

x

x

x

x

:

Block 10

x

x

x

x

:

Block 11

x

x

x

x

:

Block 12

x

x

x

x

:

Block 13

x

x

x

x

:

Block 14

x

x

x

x

:

Block 15

x

x

x

x

User Data

The values (in hexadecimal notation) shown in the table above are stored in the EEPROM after the

delivery.

5.3.1 Serial Number

The unique 64 bit serial number is stored in blocks 0 and 1 and is programmed during the

production process. SNR0 in the table represents the least significant byte and SNR7 the most

significant byte, respectively.

5.3.2 Write Access Conditions

The Write Access Condition bits in block 2 determine the write access conditions for each of the

16 blocks. These bits can be set only to 0 (and never be changed to 1), i.e. already write protected

blocks can never be written to from this moment on. This is also true for block 2. If this block is set

into write protected state by clearing of bits 4 and 5 at byte 0, no further changes in write access

conditions are possible.

Byte 0

Byte 1

Byte 2

Byte 3

âMSB

LSB

â

âMSB

LSB

â

âMSB

LSB

â

âMSB

LSB

â

Block 2:

Write Access

Conditions

|

1|1

|

|

1|1

|

|

0

|

|

0

|

|

1|1

|

|

1|1

|

|

1|1

|

|

1|1

|

|

1|1

|

|

1|1

|

|

1|1

|

|

1|1

|

|

1|1

|

|

1|1

|

|

1|1

|

|

1|1

|

for Block

à

3

2

1

0

7

6

5

4

11

10

9

8

15

14

13

12

Special

Funct.

Write

Access

Serial

Number

User

Data

Data

The ones in the 16 pairs of bits have to be cleared together if the corresponding block is wanted to

be write protected forever (1|1 à write access enabled, 0|0 à write access disabled). Writing of bit

pairs 1|0 or 0|1 to block 2 is not allowed!

It is extremely important to be particularly careful when clearing the Write Access bits in

block 2, as you can lose write access to all of the blocks on the label in case of a mistake.

Of course you can use this feature to put the label into a hardware write protected state!