m28w320bb STMicroelectronics, m28w320bb Datasheet - Page 15

• Manufacturer Part Number: m28w320bb
• Description: 32 Mbit 2mb X16, Boot Block 3v Supply Flash Memory
• Manufacturer: STMicroelectronics

STATUS REGISTER
The Status Register provides information on the
current or previous Program or Erase operation.
The various bits convey information and errors on
the operation. To read the Status register the
Read Status Register command can be issued, re-
fer to the Read Status Register Command section.
To output the contents, the Status Register is
latched on the falling edge of the Chip Enable or
Output Enable signals, and can be read until Chip
Enable or Output Enable returns to V
Chip Enable or Output Enable must be toggled to
update the latched data.
Bus Read operations from any address always
read the Status Register during Program and
Erase operations.
The bits in the Status Register are summarized in
Table 7, Status Register Bits. Refer to Table 7 in
conjunction with the following text descriptions.
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
Low (set to ‘0’), the Program/Erase Controller is
active; when the bit is High (set to ‘1’), the Pro-
gram/Erase Controller is inactive, and the device
is ready to process a new command.
The Program/Erase Controller Status is Low im-
mediately after a Program/Erase Suspend com-
mand is issued until the Program/Erase Controller
pauses. After the Program/Erase Controller paus-
es the bit is High .
During Program, Erase, operations the Program/
Erase Controller Status bit can be polled to find the
end of the operation. Other bits in the Status Reg-
ister should not be tested until the Program/Erase
Controller completes the operation and the bit is
High.
After the Program/Erase Controller completes its
operation the Erase Status, Program Status, V
Status and Block Protection Status bits should be
tested for errors.
Erase Suspend Status (Bit 6). The Erase Sus-
pend Status bit (set to ‘1’) indicates that an Erase
operation has been suspended or is going to be
suspended.
The Erase Suspend Status should only be consid-
ered valid when the Program/Erase Controller Sta-
tus bit is High (Program/Erase Controller inactive).
Bit 7 is set within 30µs of the Program/Erase Sus-
pend command being issued therefore the memo-
ry may still complete the operation rather than
entering the Suspend mode.
When a Program/Erase Resume command is is-
sued the Erase Suspend Status bit returns Low.
memory may still complete the operation rather
IH
. Either
PP
Erase Status (Bit 5). The Erase Status bit can be
used to identify if the memory has failed to verify
that the block has erased correctly. When the
Erase Status bit is High (set to ‘1’), the Program/
Erase Controller has applied the maximum num-
ber of pulses to the block and still failed to verify
that the block has erased correctly. The Erase Sta-
tus bit should be read once the Program/Erase
Controller Status bit is High (Program/Erase Con-
troller inactive).
Once set High, the Erase Status bit can only be re-
set Low by a Clear Status Register command or a
fore a new Program or Erase command is issued,
otherwise the new command will appear to fail.
Program Status (Bit 4). The Program Status bit
is used to identify a Program failure. When the
Program Status bit is High (set to ‘1’), the Pro-
gram/Erase Controller has applied the maximum
number of pulses to the byte and still failed to ver-
Status bit should be read once the Program/Erase
Controller Status bit is High (Program/Erase Con-
used to identify an invalid voltage on the V
during Program and Erase operations. The V
pin is only sampled at the beginning of a Program
or Erase operation. Indeterminate results can oc-
cur if V
When the V
age on the V
when the V
pin has a voltage that is below the V
Voltage, V
gram and Erase operations cannot be performed.
Once set High, the V
Low by a Clear Status Register command or a
hardware reset. If set High it should be reset be-
fore a new Program or Erase command is issued,
otherwise the new command will appear to fail.
Program Suspend Status (Bit 2). The Program
Suspend Status bit (set to ‘1’) indicates that a Pro-
gram operation has been suspended or is going to
be suspended.
The Program Suspend Status should only be con-
sidered valid when the Program/Erase Controller
Status bit is High (Program/Erase Controller inac-
tive). Bit 2 is set within 5µs of the Program/Erase
Suspend command being issued therefore the
than
hardware reset. If set High it should be reset be-
ify that it has programmed correctly. The Program
troller inactive).
Once set High, the Program Status bit can only be
reset Low by a Clear Status Register command or
a hardware reset. If set High it should be reset be-
fore a new command is issued, otherwise the new
command will appear to fail.
V
PP
Status (Bit 3). The V
PP
entering
becomes invalid during an operation.
PPLK
PP
PP
PP
Status bit is High (set to ‘1’), the V
Status bit is Low (set to ‘0’), the volt-
, the memory is protected and Pro-
pin was sampled at a valid voltage;
M28W320BT, M28W320BB
PP
the
Status bit can only be reset
PP
Suspend
Status bit can be
PP
Lockout
mode.
PP
15/43
pin
PP
PP