M25P80-VMW3 데이터 시트보기 (PDF) - STMicroelectronics

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M25P80-VMW3

8 Mbit, Low Voltage, Serial Flash Memory With 40MHz SPI Bus Interface

STMicroelectronics 

M25P80

Table 6. Protection Modes

W SRWD

Signal Bit

Mode

Write Protection of the

Status Register

Memory Content

Protected Area1

Unprotected Area1

1

0

Status Register is Writable

0

1

0

1

Software

Protected

(SPM)

(if the WREN instruction

has set the WEL bit)

The values in the SRWD,

BP2, BP1 and BP0 bits

Protected against Page

Program, Sector Erase

and Bulk Erase

Ready to accept Page

Program and Sector Erase

instructions

can be changed

Status Register is

Hardware Hardware write protected Protected against Page Ready to accept Page

0

1

Protected The values in the SRWD, Program, Sector Erase

Program and Sector Erase

(HPM) BP2, BP1 and BP0 bits and Bulk Erase

instructions

cannot be changed

Note: 1. As defined by the values in the Block Protect (BP2, BP1, BP0) bits of the Status Register, as shown in Table 2..

The protection features of the device are summa-

rized in Table 6..

When the Status Register Write Disable (SRWD)

bit of the Status Register is 0 (its initial delivery

state), it is possible to write to the Status Register

provided that the Write Enable Latch (WEL) bit has

previously been set by a Write Enable (WREN) in-

struction, regardless of the whether Write Protect

(W) is driven High or Low.

Status Register are rejected, and are not

accepted for execution). As a consequence,

all the data bytes in the memory area that are

software protected (SPM) by the Block Protect

(BP2, BP1, BP0) bits of the Status Register,

are also hardware protected against data

modification.

Regardless of the order of the two events, the

Hardware Protected Mode (HPM) can be entered:

When the Status Register Write Disable (SRWD)

bit of the Status Register is set to 1, two cases

need to be considered, depending on the state of

Write Protect (W):

– If Write Protect (W) is driven High, it is

possible to write to the Status Register

provided that the Write Enable Latch (WEL) bit

has previously been set by a Write Enable

(WREN) instruction.

– If Write Protect (W) is driven Low, it is not

possible to write to the Status Register even if

the Write Enable Latch (WEL) bit has

previously been set by a Write Enable

(WREN) instruction. (Attempts to write to the

– by setting the Status Register Write Disable

(SRWD) bit after driving Write Protect (W) Low

– or by driving Write Protect (W) Low after

setting the Status Register Write Disable

(SRWD) bit.

The only way to exit the Hardware Protected Mode

(HPM) once entered is to pull Write Protect (W)

High.

If Write Protect (W) is permanently tied High, the

Hardware Protected Mode (HPM) can never be

activated, and only the Software Protected Mode

(SPM), using the Block Protect (BP2, BP1, BP0)

bits of the Status Register, can be used.

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