M95010-R 查看數據表（PDF） - STMicroelectronics

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M95010-R

4Kbit, 2Kbit and 1Kbit Serial SPI Bus EEPROM With High Speed Clock

STMicroelectronics 

M95040, M95020, M95010

Status Register

Figure 7. shows the position of the Status Register

in the control logic of the device. This register con-

tains a number of control bits and status bits, as

shown in Table 3..

Bits b7, b6, b5 and b4 are always read as 1.

WIP bit. The Write In Progress bit is a volatile

read-only bit that is automatically set and reset by

the internal logic of the device. When set to a 1, it

indicates that the memory is busy with a Write cy-

cle.

WEL bit. The Write Enable Latch bit is a volatile

read-only bit that is set and reset by specific in-

structions. When reset to 0, no WRITE or WRSR

instructions are accepted by the device.

BP1, BP0 bits. The Block Protect bits are non-

volatile read-write bits. These bits define the area

of memory that is protected against the execution

of Write cycles, as summarized in Table 4..

Table 3. Status Register Format

b7

b0

1

1

1

1 BP1 BP0 WEL WIP

Block Protect Bits

Write Enable Latch Bit

Write In Progress Bit

Data Protection and Protocol Control

To help protect the device from data corruption in

noisy or poorly controlled environments, a number

of safety features have been built in to the device.

The main security measures can be summarized

as follows:

– The WEL bit is reset at power-up.

– Chip Select (S) must rise after the eighth clock

count (or multiple thereof) in order to start a

non-volatile Write cycle (in the memory array

or in the Status Register).

– Accesses to the memory array are ignored

during the non-volatile programming cycle,

and the programming cycle continues

unaffected.

– Invalid Chip Select (S) and Hold (HOLD)

transitions are ignored.

For any instruction to be accepted and executed,

Chip Select (S) must be driven High after the rising

edge of Serial Clock (C) that latches the last bit of

the instruction, and before the next rising edge of

Serial Clock (C).

For this, “the last bit of the instruction” can be the

eighth bit of the instruction code, or the eighth bit

of a data byte, depending on the instruction (ex-

cept in the case of RDSR and READ instructions).

Moreover, the "next rising edge of CLOCK" might

(or might not) be the next bus transaction for some

other device on the bus.

When a Write cycle is in progress, the device pro-

tects it against external interruption by ignoring

any subsequent READ, WRITE or WRSR instruc-

tion until the present cycle is complete.

Table 4. Write-Protected Block Size

Status Register Bits

BP1

BP0

Protected Block

0

0

none

0

1

Upper quarter

1

0

Upper half

1

1

Whole memory

Array Addresses Protected

M95040

M95020

none

none

180h - 1FFh

C0h - FFh

100h - 1FFh

80h - FFh

000h - 1FFh

00h - FFh

M95010

none

60h - 7Fh

40h - 7Fh

00h - 7Fh

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