M50FLW040A datasheet(20/52 Pages) STMICROELECTRONICS

20 / 52 page

M50FLW040A, M50FLW040B

20/52

See Figure 27., for a suggested flowchart on using

the Block Erase command. Typical Block Erase

times are given in Table 18..

Sector Erase Command. The

Sector

Erase

command is used to erase a Uniform 4-KByte Sec-

tor, setting all of the bits to ‘1’. All previous data in

the sector are lost.

Two Bus Write operations are required to issue the

command. The second Bus Write cycle latches the

Sector address and starts the Program/Erase

Controller. Once the command is issued, subse-

quent Bus Read operations read the contents of

the Status Register. (See the section on the Status

If the Block to which the Sector belongs is protect-

ed (FWH/LPC only) then the Sector Erase opera-

tion will abort, the data in the Sector will not be

changed, and the Status Register will indicate the

error.

During the Sector Erase operation the memory will

only accept the Read Status Register and Pro-

gram/Erase Suspend commands. All other com-

mands are ignored.

See Figure 27., for a suggested flowchart on using

the Sector Erase Command. Typical Sector Erase

times are given in Table 18..

Clear Status Register Command. The

Clear

Status Register command is used to reset Status

Bus Write is required to issue the command. Once

the command is issued, the device returns to its

previous mode, subsequent Bus Read operations

continue to output the data from the same area, as

before.

Once set, these Status Register bits remain set.

They do not automatically return to ‘0’, for exam-

ple, when a new program or erase command is is-

sued. If an error has occurred, it is essential that

any error bits in the Status Register are cleared, by

issuing the Clear Status Register command, be-

fore attempting a new program or erase com-

mand.

Program/Erase Suspend Command. The Pro-

gram/Erase Suspend command is used to pause

the Program/Erase Controller during a program or

Sector/Block Erase operation. One Bus Write cy-

cle is required to issue the command.

Once the command has been issued, it is neces-

sary to poll the Program/Erase Controller Status

bit until the Program/Erase Controller has paused.

No other commands are accepted until the Pro-

gram/Erase Controller has paused. After the Pro-

gram/Erase Controller has paused, the device

continues to output the contents of the Status Reg-

ister until another command is issued.

During the polling period, between issuing the Pro-

gram/Erase Suspend command and the Program/

Erase Controller pausing, it is possible for the op-

eration to complete. Once the Program/Erase

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.

During Program/Erase Suspend, the Read Memo-

ry Array, Read Status Register, Read Electronic

Signature and Program/Erase Resume com-

mands will be accepted by the Command Inter-

face. Additionally, if the suspended operation was

Sector Erase or Block Erase then the program

command will also be accepted. However, it

should be noted that only the Sectors/Blocks not

being erased may be read or programmed correct-

ly.

See Figure 25., and Figure 28., for suggested

flowcharts on using the Program/Erase Suspend

command. Typical times and delay durations are

given in Table 18..

Program/Erase Resume Command. The

Pro-

gram/Erase Resume command can be used to re-

start

the

Program/Erase

Controller

after

Program/Erase Suspend has paused it. One Bus

Write cycle is required to issue the command.

Once the command is issued, subsequent Bus

Read operations read the contents of the Status

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