M95256-R datasheet(24/51 Pages) STMICROELECTRONICS

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6.9

Read Lock status (available only in M95256-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 following figure shows the instruction 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

M95256-W M95256-R M95256-DF

Read Lock status (available only in M95256-D devices)

DS4712 - Rev 22

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M95256-R 데이터시트(PDF) 24 Page - STMicroelectronics