M24LRxx’s conditional memory access

AN3002

16/22

Doc ID 15912 Rev 2

Through the setting of bits b1 & b2 (see Table 5: Read / Write protection bit setting), it is

possible to:

●

write-protect a sector, in which case the sector’s data is read-only

●

read-protect a sector, in which case the sector’s data is not accessible from the RF

In the following example, the initial setting of the M24LRxx is described in Table 13. Sectors

0 to 3 are protected against various read and write access conditions as defined by the

values of their Sector security status bits, b1 and b2.

M24LRxx memory access after RF power-on

After a correct RF power-on condition, the M24LRxx offers the sector access conditions

shown in Table 13: RF memory access conditions at power-on. All the memory sectors can

be read except for sectors 2 & 3, and write operations are allowed on all the sectors except

for sectors 0, 2 & 3.

Table 13.

RF memory access conditions at power-on

Access condition

M24LRxx user memory

SSS byte

Read only

Sector 0

0000 1001b

Read and Write

Sector 1

0000 1011b

Not accessible

Sector 2

0000 1101b

Not accessible

Sector 3

0000 1111b

Read and Write

…

0000 0000b

Read and Write

Sector 62

0000 0000b

Read and Write

Sector 63

0000 0000b

Not accessible in RF

I2C_Write lock bit area

Not applicable

Write once in RF

Sector_Security_Status area

Not applicable