M36W432T Datasheet, PDF (18/57 Pages) STMicroelectronics – 32 Mbit 2Mb x16, Boot Block Flash Memory and 4 Mbit 256K x16 SRAM, Multiple Memory Product

M36W432T, M36W432B
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.
Table 8. Block Lock Status
Item
Block Lock Configuration
Block is Unlocked
Block is Locked
Block is Locked-Down
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.
Address
xx002
Data
LOCK
DQ0=0
DQ0=1
DQ1=1
Table 9. Lock Status
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⁾
no
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
no
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⁾
no
0,0,1
0,0,0
0,1,1
1,0,1
0,1,1
no
0,1,1
0,1,1
0,1,1
1,1,1 or 1,1,0 ⁽³⁾
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 = V_IH and A0 = V_IL.
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 V_IH on a locked block will restore the previous DQ0 value, giving a 111 or 110.
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