M95320-W datasheet(21/48 Pages) STMICROELECTRONICS

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M95320-W M95320-R M95320-DR

Instructions

Doc ID 5711 Rev 14

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Driving the Chip Select (S) signal high at a byte boundary of the input data triggers the self-

timed Write cycle that takes tW to complete (as specified in AC tables under Section 9: DC

and AC parameters).

While the Write Status Register cycle is in progress, the Status Register may still be read to

check the value of the Write in progress (WIP) bit: the WIP bit is 1 during the self-timed

Write cycle tW, and 0 when the Write cycle is complete. The WEL bit (Write Enable Latch) is

also reset at the end of the Write cycle tW.

The Write Status Register (WRSR) instruction enables the user to change the values of the

BP1, BP0 and SRWD bits:

●

The Block Protect (BP1, BP0) bits define the size of the area that is to be treated as

read-only, as defined in Table 2.

●

The SRWD (Status Register Write Disable) bit, in accordance with the signal read on

the Write Protect pin (W), enables the user to set or reset the Write protection mode of

the Status Register itself, as defined in Table 7. When in Write-protected mode, the

Write Status Register (WRSR) instruction is not executed.

The contents of the SRWD and BP1, BP0 bits are updated after the completion of the

WRSR instruction, including the tW Write cycle.

The Write Status Register (WRSR) instruction has no effect on the b6, b5, b4, b1, b0 bits in

the Status Register. Bits b6, b5, b4 are always read as 0.

The protection features of the device are summarized in Table 7.

When the Status Register Write Disable (SRWD) bit in the Status Register is 0 (its initial

delivery state), it is possible to write to the Status Register (provided that the WEL bit has

previously been set by a WREN instruction), regardless of the logic level applied on the

Write Protect (W) input pin.

Table 7.

Protection modes

signal

SRWD

bit

Mode

Write protection of the

Status Register

Memory content

Protected area(1)

As defined by the values in the Block Protect (BP1, BP0) bits of the Status Register. See Table 2.

Unprotected area(1)

Software-

protected

(SPM)

Status Register is

writable (if the WREN

instruction has set the

WEL bit).

The values in the BP1

and BP0 bits can be

changed.

Write-protected

Ready to accept

Write instructions

Hardware-

protected

(HPM)

Status Register is

Hardware write-

protected.

The values in the BP1

and BP0 bits cannot be

changed.

Write-protected

Ready to accept

Write instructions

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