M50FLW040AN5TP datasheet(22/52 Pages) STMICROELECTRONICS

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M50FLW040A, M50FLW040B

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STATUS REGISTER

The Status Register provides information on the

current or previous Program or Erase operation.

The bits in the Status Register convey specific in-

formation about the progress of the operation.

To read the Status Register, the Read Status Reg-

ister 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 ad-

dress.

The text descriptions, below, should be read in

conjunction with Table 14., where the meanings of

the Status Register bits are summarized.

Program/Erase Controller Status (Bit SR7).

This bit indicates whether the Program/Erase Con-

troller is active or inactive. When the Program/

Erase Controller Status bit is ‘0’, the Program/

Erase Controller is active; when the bit is ‘1’, the

Program/Erase Controller is inactive.

The Program/Erase Controller Status is ‘0’ imme-

diately after a Program/Erase Suspend command

is issued, until the Program/Erase Controller paus-

es. After the Program/Erase Controller pauses,

the bit is ‘1’.

The end of a Program and Erase operation can be

found by polling the Program/Erase Controller

Status bit can be polled. The other bits in the Sta-

tus Register should not be tested until the Pro-

gram/Erase

Controller

has

completed

the

operation (and the Program/Erase Controller Sta-

tus bit is ‘1’).

After the Program/Erase Controller has completed

its operation, the Erase Status, Program Status,

VPP Status and Block Protection Status bits should

be tested for errors.

Erase Suspend Status (Bit SR6). This bit indi-

cates that an Erase operation has been suspend-

ed, and that it is waiting to be resumed. The Erase

Suspend Status should only be considered valid

when the Program/Erase Controller Status bit is ‘1’

(Program/Erase Controller inactive). After a Pro-

gram/Erase Suspend command is issued, the

memory may still complete the operation rather

than entering the Suspend mode.

When the Erase Suspend Status bit is ‘0’, the Pro-

gram/Erase Controller is active or has completed

its operation. When the bit is ‘1’, a Program/Erase

Suspend command has been issued and the

memory is waiting for a Program/Erase Resume

command.

When a Program/Erase Resume command is is-

sued, the Erase Suspend Status bit returns to ‘0’.

Erase Status (Bit SR5). This bit indicates if a

problem has occurred during the erasing of a Sec-

tor or Block. The Erase Status bit should be read

once the Program/Erase Controller Status bit is ‘1’

(Program/Erase Controller inactive).

When the Erase Status bit is ‘0’, the memory has

successfully verified that the Sector/Block has

been erased correctly. When the Erase Status bit

is ‘1’, the Program/Erase Controller has applied

the maximum number of pulses to the Sector/

Block and still failed to verify that the Sector/Block

has been erased correctly.

Once the Erase Status bit is set to ‘1’, it can only

be reset to ‘0’ by a Clear Status Register com-

mand, or by a hardware reset. If it is set to ‘1’, it

should be reset before a new Program or Erase

command is issued, otherwise the new command

will appear to have failed, too.

Program Status (Bit SR4). This bit indicates if a

problem has occurred during the programming of

a byte. The Program Status bit should be read

once the Program/Erase Controller Status bit is ‘1’

(Program/Erase Controller inactive).

When the Program Status bit is ‘0’, the memory

has successfully verified that the byte has been

programmed correctly. When the Program Status

bit is ‘1’, the Program/Erase Controller has applied

the maximum number of pulses to the byte and still

failed to verify that the byte has been programmed

correctly.

Once the Program Status bit is set to ‘1’, it can only

be reset to ‘0’ by a Clear Status Register com-

mand, or by a hardware reset. If it is set to ‘1’, it

should be reset before a new Program or Erase

command is issued, otherwise the new command

will appear to have failed, too.

VPP Status (Bit SR3). This bit indicates whether

an invalid voltage was detected on the VPP pin at

the beginning of a Program or Erase operation.

The VPP pin is only sampled at the beginning of

the operation. Indeterminate results can occur if

VPP becomes invalid during a Program or Erase

operation.

Once the VPP Status bit set to ‘1’, it can only be re-

set to ‘0’ by a Clear Status Register command, or

by a hardware reset. If it is set to ‘1’, it should be

reset before a new Program or Erase command is

issued, otherwise the new command will appear to

have failed, too.

Program Suspend Status (Bit SR2). This bit in-

dicates that a Program operation has been sus-

pended, and that it is waiting to be resumed. The

Program Suspend Status should only be consid-

ered valid when the Program/Erase Controller Sta-

tus bit is ‘1’ (Program/Erase Controller inactive).

After a Program/Erase Suspend command is is-

sued, the memory may still complete the operation

instead of entering the Suspend mode.

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