P R E L I M I N A R Y
Table 6. Hardware Sequence Flags
Status
DQ7
DQ7
0
DQ6
DQ5
DQ3
DQ2
RY/BY
Programming
Toggle
Toggle
0
0
0
1
No Toggle
(Note 1)
0
0
Program/Erase in Auto-Erase
Toggle
(Note 1)
Erase Sector Address
Erase
Suspend
1
No Toggle
Data
0
Data
0
0
Data
0
1
1
0
In Progress
Data(Note
2)
Mode
Non-Erase Sector Address
Data
DQ7
(Note 2)
1
Program in Erase Suspend
Toggle
(Note 2)
Programming
DQ7
0
Toggle
Toggle
Toggle
1
1
1
0
1
0
No Toggle
(Note 3)
0
0
0
Exceeded
Time Limits
Program/Erase in Auto-Erase
Program in Erase Suspend
DQ7
No Toggle
Notes:
1. DQ2 can be toggled when the sector address applied is that of an erasing or erase suspended sector.Conversely, DQ2 cannot
be toggled when the sector address applied is that of a non-erasing or non-erase suspended sector. DQ2 is therefore used
to determine which sectors are erasing or erase suspended and which are not.
2. These status flags apply when outputs are read from the address of a non-erase-suspended sector.
3. If DQ5 is high (exceeded timing limits), successive reads from a problem sector will cause DQ2 to toggle.
DQ7: Data Polling
device is driving status information on DQ7 at one in-
stant of time and in the next instance of time, that byte
has valid data. Depending on when the system sam-
ples the DQ7 output, it may read the status or valid
data. Even if the device has completed the Embedded
Algorithm operations and DQ7 has valid data, DQ0–
DQ6 may still provide write operation status. The valid
data on DQ0–DQ7 can be read on the next successive
read attempt.
The Am29LV008 features DATA Polling as a method to
indicate to the host system that the embedded algo-
rithms are in progress or completed.
During the Embedded Program Algorithm, an attempt
to read the device will produce the compliment of the
data last written to DQ7. Upon completion of the Em-
bedded Program Algorithm, an attempt to read the de-
vice will produce the true data last written to DQ7. Note
that just at the instant when DQ7 switches to true data,
the other bits, DQ6–DQ0, may not yet be true data.
However, they will all be true data on the next read from
the device. Please note that Data Polling (DQ7) may
give an inaccurate result when an attempt is made
to write to a protected sector. During an Embedded
Erase Algorithm, an attempt to read the device will pro-
duce a ‘0’ at the DQ7 output. Upon completion of the
Embedded Erase Algorithm, an attempt to read
the device will produce a ‘1’ at DQ7.
The DATA Polling feature is only active during the Em-
bedded Programming Algorithm, Embedded Erase Al-
gorithm, Erase Suspend, erase suspend-program
mode, or sector erase time-out (see Table 6).
If the user attempts to write to a protected sector, DATA
Polling will be activated for about 1 µs; the device will
then return to read mode, with data from the protected
sector unchanged. If the user attempts to erase a pro-
tected sector, Toggle Bit will be activated for about 50
µs; the device will then return to read mode, without
having erased the protected sector.
For chip erase, the DATA Polling is valid (DQ7 = 1) after
the rising edge of the sixth WE pulse in the six write
pulse sequence. For sector erase, the DATA Polling is
valid after the last rising edge of the sector erase WE
pulse. DATA Polling must be performed at sector ad-
dresses within any of the sectors being erased and not
a sector that is within a protected sector. Otherwise, the
status may not be valid.
See Figure 6 for the DATA Polling timing specifications
and diagrams.
DQ6:Toggle Bit
The Am29LV008 also features a “Toggle Bit” as a
method to indicate to the host system whether the em-
bedded algorithms are in progress or completed.
Just prior to the completion of Embedded Algorithm op-
erations, DQ7 may change asynchronously while the
output enable (OE) is asserted low.This means that the
During an Embedded Program or Erase Algorithm,
successive attempts to read data from the device will
result in DQ6 toggling between one and zero. Once the
16
Am29LV008T/Am29LV008B
CYPRESS [ CYPRESS ]
