AN3002

User memory organization

Doc ID 15912 Rev 2

5/22

1

User memory organization

The M24LRxx is divided into 64 sectors of 32 blocks of 32 bits. Figure 2 shows the memory

sector organization. Each sector can be individually read- and/or write-protected using a

specific password command. Read and write operations are possible if the addressed data

is not in a protected sector.

The M24LRxx also has a 64-bit block that is used to store the 64-bit unique identifier (UID).

The UID is compliant with the ISO 15963 description, and its value is used during the

anticollision sequence (Inventory). This block is not accessible by the user and its value is

written by ST on the production line.

The M24LRxx includes an AFI register that stores the application family identifier, and a

DSFID register that stores the data storage family identifier used in the anticollision

algorithm.

password codes.

Figure 2.

Memory sector organization

Sector details

The M24LRxx user memory is divided into 64 sectors. Each sector contains 1024 bits.

In RF mode, a sector provides 32 blocks of 32 bits. Each read / write access is done by

block. Read and write block accesses are controlled by a Sector security status byte that

defines the access rights to all the 32 blocks contained in the sector. If the sector is not

protected, a Write command updates all 32 bits of the selected block.

0

1 Kbit EEPROM sector

5 bits

1

1 Kbit EEPROM sector

5 bits

2

1 Kbit EEPROM sector

5 bits

3

1 Kbit EEPROM sector

5 bits

60

1 Kbit EEPROM sector

5 bits

61

1 Kbit EEPROM sector

5 bits

62

1 Kbit EEPROM sector

5 bits

63

1 Kbit EEPROM sector

5 bits

I2C Password

System

RF Password 1

System

RF Password 2

System

RF Password 3

System

8 bit DSFID

System

8 bit AFI

System

64 bit UID

System

Sector

Area

Sector security

status

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