M95128-DF datasheet(21/48 Pages) STMICROELECTRONICS

21 / 48 page

6.8

Write Identification page (available only in M95128-D devices)

The Identification page (64 bytes) is an additional page that can be written and (later) permanently locked in

Read-only mode.

Writing this page is achieved with the Write Identification page instruction (see Table 4. Instruction set). The Chip

select signal (S) is first driven low. The bits of the instruction byte, address bytes, and at least one data byte are

then shifted in on Serial data input (D). Address bit A10 must be 0, upper address bits are Don't care, the lower

address bits [A5:A0] define the byte address within the Identification page. The instruction sequence is shown in

Figure 16. Write Identification page sequence.

Figure 16. Write Identification page sequence

9 10

20 21 22 23 24 25 26 27

14 13

28 29 30

High impedance

Instruction

16-bit address

Data byte

6.9

Read Lock status (available only in M95128-D devices)

The Read Lock status instruction (see Table 4. Instruction set) is used to check whether the Identification page is

locked or not in Read-only mode. The Read Lock status sequence is defined with the Chip select (S) first driven

low. The bits of the instruction byte and address bytes are then shifted in on Serial data input (D). Address bit A10

must be 1, all other address bits are Don't Care. The Lock bit is the LSB (least significant bit) of the byte read on

Serial data output (Q). It is at “1” when the lock is active and at “0” when the lock is not active. If Chip select (S)

continues to be driven low, the same data byte is shifted out. The read cycle is terminated by driving Chip select

(S) high.

The instruction sequence is shown in Figure 17. Read Lock status sequence.

Figure 17. Read Lock status sequence

9 10

20 21 22 23 24 25 26 27

14 13

28 29 30

High impedance

Data Out 1

Instruction

16-bit address

MSB

Data Out 2

M95128-W M95128-R M95128-DF

Write Identification page (available only in M95128-D devices)

DS1356 - Rev 20

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