M50LPW041K データシートの表示（PDF） - STMicroelectronics

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M50LPW041K

4 Mbit (512Kb x8, Uniform Block) 3V Supply Low Pin Count Flash Memory

STMicroelectronics 

M50LPW041

Block Erase Command. The Block Erase com-

mand can be used to erase a block. Two Bus Write

operations are required to issue the command; the

second Bus Write cycle latches the block address

in the internal state machine and starts the Pro-

gram/Erase Controller. Once the command is is-

sued subsequent Bus Read operations read the

Status Register. See the section on the Status

Register for details on the definitions of the Status

Register bits.

If the block is protected then the Block Erase

operation will abort, the data in the block will not be

changed and the Status Register will output the

error.

During the Block Erase operation the memory will

only accept the Read Status Register command

and the Program/Erase Suspend command. All

other commands will be ignored. Typical Block

Erase times are given in Table 13.

The Block Erase command sets all of the bits in

the block to ‘1’. All previous data in the block is

lost.

See Figure 18, Block Erase Flowchart and Pseudo

Code, for a suggested flowchart on using the

Block Erase command.

Clear Status Register Command. The Clear Sta-

tus Register command can be used to reset bits 1,

3, 4 and 5 in the Status Register to ‘0’. One Bus

Write is required to issue the Clear Status Register

command. Once the command is issued the mem-

ory returns to its previous mode, subsequent Bus

Read operations continue to output the same data.

The bits in the Status Register are sticky and do

not automatically return to ‘0’ when a new Program

or Erase command is issued. If an error occurs

then it is essential to clear any error bits in the Sta-

tus Register by issuing the Clear Status Register

command before attempting a new Program or

Erase command.

Program/Erase Suspend Command. The Pro-

gram/Erase Suspend command can be used to

pause a Program or Block Erase operation. One

Bus Write cycle is required to issue the Program/

Erase Suspend command and pause the Pro-

gram/Erase Controller. Once the command is is-

sued it is necessary to poll the Program/Erase

Controller Status bit to find out when the Program/

Erase Controller has paused; no other commands

will be accepted until the Program/Erase Control-

ler has paused. After the Program/Erase Control-

ler has paused, the memory will continue to output

the Status Register until another command is is-

sued.

During the polling period between issuing the

Program/Erase Suspend command and the

Program/Erase Controller pausing it is possible for

the operation to complete. Once Program/Erase

Table 11. Read Electronic Signature

Code

Address

Manufacturer Code

00000h

Device Code

Note: For A19 value, see Table 2.

00001h

Data

20h

3Ch

Controller Status bit indicates that the Program/

Erase Controller is no longer active, the Program

Suspend Status bit or the Erase Suspend Status

bit can be used to determine if the operation has

completed or is suspended. For timing on the

delay between issuing the Program/Erase

Suspend command and the Program/Erase

Controller pausing see Table 13.

During Program/Erase Suspend the Read

Memory Array, Read Status Register, Read

Electronic Signature and Program/Erase Resume

commands will be accepted by the Command

Interface. Additionally, if the suspended operation

was Block Erase then the Program command will

also be accepted; only the blocks not being erased

may be read or programmed correctly.

See Figures 16, Program Suspend & Resume

Flowchart and Pseudo Code, and 19, Erase

Suspend & Resume Flowchart and Pseudo Code,

for suggested flowcharts on using the Program/

Erase Suspend command.

Program/Erase Resume Command. The Pro-

gram/Erase Resume command can be used to re-

start the Program/Erase Controller after a

Program/Erase Suspend has paused it. One Bus

Write cycle is required to issue the Program/Erase

Resume command. Once the command is issued

subsequent Bus Read operations read the Status

Register.

STATUS REGISTER

The Status Register provides information on the

current or previous Program or Erase operation.

Different bits in the Status Register convey

different information and errors on the operation.

To read the Status Register the Read Status

Register command can be issued. The Status

Register is automatically read after Program,

Erase and Program/Erase Resume commands

are issued. The Status Register can be read from

any address.

The Status Register bits are summarized in Table

14, Status Register Bits. Refer to Table 14 in con-

junction with the text descriptions below.

Program/Erase Controller Status (Bit 7). The Pro-

gram/Erase Controller Status bit indicates whether

the Program/Erase Controller is active or inactive.

When the Program/Erase Controller Status bit is

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