M24M02E-F datasheet(9/54 Pages) STMICROELECTRONICS

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Table 8. Software write protection register description

Bit

Function

Bits b7 to b4

•

Don’t care bits. Read as 0. (b7, b6, b5, b4) = (0, 0, 0, 0)

Bits b3

WPA: Write protect activation bit.

b3 enables or disables the write protection:

•

b3 = 0: no write protection. The whole memory can be written.

•

b3 = 1: write protection active. The memory block is protected according to BP bits setting.

Bits b2 to b1

BP1, BP0: block protection bits

b2 and b1 define the size of the memory block to be protected against write instruction:

•

(b2, b1) = (0, 0): the upper quarter of memory is write-protected

•

(b2, b1) = (0, 1): the upper half of memory is write protected

•

(b2, b1) = (1, 0): the upper ¾ of memory is write protected

•

(b2, b1) = (1, 1): the whole memory is write protected

Bit b0

WPL: write protection lock bit

b0 locks the write protection register value.

•

b0 = 0: bits [b3: b0] can be modified

•

b0 = 1: bits [b3: b0] cannot be modified and therefore the write protection register is frozen.

Note: bits b3 to b0 can be updated (if b0 = 0) in the same write instruction. Setting b0 from 0 to 1 is an

irreversible action.

4.4

Identification page

The identification page (256-byte) is an additional page that can be read or written and can later be permanently

locked in read-only mode. It is read or written by issuing the read or write identification page instruction. These

instructions use the same protocol and format as the random address read or page write (from memory array)

except for the following differences (refer to Table 9, Table 10, and Table 11):

•

Device type identifier = 1011

•

MSB address bits A15, A14, and A13 must be equal to 000

•

MSB address bits from A12 to A8 are don't care

•

LSB address bits from A7 to A0 define the byte address inside the identification page

If the identification page is locked, the data bytes transferred during the write identification page instruction are not

acknowledged (NO ACK).

The identification page is filled with all bytes written to FFh.

M24M02E-F

Device features

DS14157 - Rev 2

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