P R E L I M I N A R Y
read or programs in a sector not being erased. This
■ Checking the status of the toggle bit DQ2
■ Checking the status of the RY/BY pin
command is applicable only during the Sector Erase
operation, which includes the time-out period for Sector
Erase. The Erase Suspend command will be ignored if
written during the execution of the Chip Erase opera-
tion or Embedded Program Algorithm (but will reset the
chip if written improperly during the command se-
quences.) Writing the Erase Suspend command during
the Sector Erase time-out results in immediate termina-
tion of the time-out period and suspension of the erase
operation. Once in Erase Suspend, the device is avail-
able for read (note that in the Erase Suspend mode, the
Reset/Read command is not required for read opera-
tions and is ignored) or program operations in sectors
not being erased. Any other command written during
the Erase Suspend mode will be ignored, except for the
Erase Resume command. Writing the Erase Resume
command resumes the sector erase operation.The ad-
dresses are “don’t cares” when writing the Erase Sus-
pend or Erase Resume command.
To resume the operation of Sector Erase, the Resume
command (30H) should be written. Any further writes of
the Resume command at this point will be ignored.
However, another Erase Suspend command can be
written after the device has resumed sector erase op-
erations.
When the erase operation has been suspended, the
device defaults to the erase-suspend-read mode.
Reading data in this mode is the same as reading from
the standard read mode except that the data must be
read from sectors that have not been
erase-suspended.
To resume the operation of Sector Erase, the Resume
command (30H) should be written. Any further writes of
the Resume command at this point will be ignored. An-
other Erase Suspend command can be written after the
chip has resumed erasing.
When the Erase Suspend command is written during a
Sector Erase operation, the chip will take between 0.1
µs and 20 µs to actually suspend the operation and go
into erase suspended read mode (pseudo-read mode),
at which time the user can read or program from a sec-
tor that is not erase suspended. Reading data in this
mode is the same as reading from the standard read
mode, except that the data must be read from sectors
that have not been erase suspended.
Write Operation Status
Address Sensitivity of Write Status Flags
Detailed in Table 6 are all the status flags that can be
used to check the status of the device for current mode
operation. During Sector Erase, the part provides the
status flags automatically to the I/O ports.The informa-
tion on DQ2 is address sensitive. This means that if an
address from an erasing sector is consecutively read,
then the DQ2 bit will toggle. However, DQ2 will not tog-
gle if an address from a non-erasing sector is consec-
utively read. This allows the user to determine which
sectors are erasing and which are not.
Successively reading from the erase-suspended sector
while the device is in the erase-suspend-read mode will
cause DQ2 to toggle. Polling DQ2 on successive reads
from a given sector provides the system the ability to
determine if a sector is in Erase Suspend.
Once Erase Suspend is entered, address sensitivity
still applies. If the address of a non-erasing sector (that
is, one available for read) is provided, then stored data
can be read from the device. If the address of an eras-
ing sector (that is, one unavailable for read) is applied,
the device will output its status bits. Confirmation of sta-
tus bits can be done by doing consecutive reads to tog-
gle DQ2, which is active throughout the Embedded
Erase mode, including Erase Suspend.
After entering the erase-suspend-read mode, the user
can program the device by writing the appropriate com-
mand sequence for Byte Program. This program mode
is known as the erase suspend-program mode. Again,
programming in this mode is the same as programming
in the regular Byte Program mode, except that the data
must be programmed to sectors that are not erase sus-
pended. Successively reading from the erase sus-
pended sector while the device is in the erase
suspend-program mode will cause DQ2 to toggle.
Completion of the erase suspend operation can be de-
termined two ways:
In order to effectively use DATA Polling to determine if
the device has entered into erase-suspended mode, it
is necessary to apply a sector address from a sector
being erased.
Am29LV008T/Am29LV008B
15
CYPRESS [ CYPRESS ]
