M24LR04E-R datasheet(24/142 Pages) STMICROELECTRONICS

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System memory area

M24LR04E-R

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Doc ID 022208 Rev 5

The M24LR04E-R password protection is organized around a dedicated set of commands,

plus a system area of three password blocks where the password values are stored. This

system area is described in Table 10.

The dedicated commands for protection in RF mode are:

●

Write-sector password:

The Write-sector password command is used to write a 32-bit block into the password

system area. This command must be used to update password values. After the write

cycle, the new password value is automatically activated. It is possible to modify a

password value after issuing a valid Present-sector password command. On delivery,

the three default password values are set to 0000 0000h and are activated.

●

Lock-sector:

The Lock-sector command is used to set the sector security status byte of the selected

sector. Bits b4 to b1 of the sector security status byte are affected by the Lock-sector

command. The sector lock bit, b0, is set to 1 automatically. After issuing a Lock-sector

command, the protection settings of the selected sector are activated. The protection of

a locked block cannot be changed in RF mode. A Lock-sector command sent to a

locked sector returns an error code.

Table 9.

Password control bits

b4, b3

Password

The sector is not protected by a password.

The sector is protected by password 1.

The sector is protected by password 2.

The sector is protected by password 3.

Table 10.

Password system area

Add

Password 1

Password 2

Password 3

M24LR04E-R Datasheet(PDF) 24 Page - STMicroelectronics