M50FW002K1T datasheet(15/39 Pages) STMICROELECTRONICS

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M50FW002

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

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

10, Status Register Bits. Refer to Table 10 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

‘0’, the Program/Erase Controller is active; when

the bit is ‘1’, the Program/Erase Controller is inac-

tive.

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’.

During Program and Erase operation the Pro-

gram/Erase Controller Status bit can be polled to

find the end of the operation. The other bits in the

Status Register should not be tested until the Pro-

gram/Erase Controller completes the operation

and the bit is ‘1’.

After the Program/Erase Controller completes its

operation the Erase Status, Program Status, VPP

Status and Block Protection Status bits should be

tested for errors.

Erase Suspend Status (Bit 6). The Erase Sus-

pend Status bit indicates that an Erase operation

has been suspended and is waiting to be re-

sumed. The Erase Suspend Status should only be

considered valid when the Program/Erase Con-

troller Status bit is ‘1’ (Program/Erase Controller

inactive); after a Program/Erase Suspend com-

mand 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 5). The Erase Status bit can be

used to identify if the memory has applied the

maximum number of erase pulses to the block and

still failed to verify that the block has erased cor-

rectly. The Erase Status bit should be read once

the Program/Erase Controller Status bit is ‘1’ (Pro-

gram/Erase Controller inactive).

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

successfully verified that the block has erased cor-

rectly; when the Erase Status bit is ‘1’ the Pro-

gram/Erase Controller has applied the maximum

number of pulses to the block and still failed to ver-

ify that the block has erased correctly.

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

reset to ‘0’ by a Clear Status Register command or

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

before a new Program or Erase command is is-

sued, otherwise the new command will appear to

fail.

Program Status (Bit 4). The Program Status bit

can be used to identify if the memory has applied

the maximum number of program pulses to the

byte and still failed to verify that the byte has pro-

grammed correctly. 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 pro-

grammed 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 programmed cor-

rectly.

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

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

mand or 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 fail.

VPP Status (Bit 3). The VPP Status bit can be

used to identify an invalid voltage on the VPP pin

during Program and Erase operations. The VPP

pin is only sampled at the beginning of a Program

or Erase operation. Indeterminate results can oc-

cur if VPP becomes invalid during a Program or

Erase operation.

When the VPP Status bit is ‘0’ the voltage on the

VPP pin was sampled at a valid voltage; when the

VPP Status bit is ‘1’ the VPP pin has a voltage that

is below the VPP Lockout Voltage, VPPLK, the

memory is protected; Program and Erase opera-

tion cannot be performed.

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

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

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

before a new Program or Erase command is is-

sued, otherwise the new command will appear to

fail.

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