M36W432B datasheet(18/57 Pages) STMICROELECTRONICS

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M36W432T, M36W432B

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Reading a Block’s Lock Status. The lock status

of every block can be read in the Read Electronic

Signature mode of the device. To enter this mode

write 90h to the device. Subsequent reads at Block

Address 00002h will output the lock status of that

block. The lock status is represented by DQ0 and

DQ1. DQ0 indicates the Block Lock/Unlock status

and is set by the Lock command and cleared by

the Unlock command. it is also automatically set

when entering Lock-Down. DQ1 indicates the

Lock-Down status and is set by the Lock-Down

command. It cannot be cleared by software, only

by a device reset or power-down.

Locking Operations During Erase Suspend.

Changes to block lock status can be performed

during an erase suspend by using the standard

locking command sequences to unlock, lock or

lock-down a block. This is useful in the case when

another block needs to be updated while an erase

operation is in progress.

To change block locking during an erase opera-

tion, first write the Erase Suspend command, then

check the status register until it indicates that the

erase operation has been suspended. Next write

the desired Lock command sequence to a block

and the lock status will be changed. After complet-

ing any desired lock, read, or program operations,

resume the erase operation with the Erase Re-

sume command.

If a block is locked or locked-down during an erase

suspend of the same block, the locking status bits

will be changed immediately, but when the erase

is resumed, the erase operation will complete.

Locking operations cannot be performed during a

program suspend. Refer to Appendix D, Com-

mand Interface and Program/Erase Controller

State, for detailed information on which com-

mands are valid during erase suspend.

Table 8. Block Lock Status

Table 9. Lock Status

Note: 1. The lock status is defined by the write protect pin and by DQ1 (‘1’ for a locked-down block) and DQ0 (‘1’ for a locked block) as read

in the Read Electronic Signature command with A1 = VIH andA0=VIL.

2. All blocks are locked at power-up, so the default configuration is 001 or 101 according to WPF status.

3. A WPF transition to VIH on a locked block will restore the previous DQ0 value, giving a 111 or 110.

Item

Address

Data

Block Lock Configuration

xx002

LOCK

Block is Unlocked

DQ0=0

Block is Locked

DQ0=1

Block is Locked-Down

DQ1=1

Current

Lock Status(1)

(WPF,DQ1,DQ0)

Next Lock Status(1)

(WPF, DQ1, DQ0)

Current State

Program/Erase

Allowed

After

Block Lock

Command

After

Block Unlock

Command

After Block

Lock-Down

Command

After

WPF transition

1,0,0

yes

1,0,1

1,0,0

1,1,1

0,0,0

1,0,1(2)

1,0,1

1,0,0

1,1,1

0,0,1

1,1,0

yes

1,1,1

1,1,0

1,1,1

0,1,1

1,1,1

1,1,0

1,1,1

0,1,1

0,0,0

yes

0,0,1

0,0,0

0,1,1

1,0,0

0,0,1(2)

0,0,1

0,0,0

0,1,1

1,0,1

0,1,1

1,1,1 or 1,1,0 (3)

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