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CHAPTER 16 FLASH MEMORY
Temporary sector erase stop status
When a read operation is performed during temporary sector erase stop, flash memory outputs
"1" if the address indicated by the address signal is included in the sector in erase state. If the
address is not included in the sector in erase state, flash memory outputs the data of bit 7 of the
read value at the address indicated by the address signal.
For checking whether a sector is in temporary sector erase stop state and when determining
which sector is in erase state, read toggle bit 6, which is described later.
<Note>
When the automatic algorithm approaches the end of its operation, bit 7 (data polling)
asynchronously varies during a read operation, which means that flash memory outputs
operation status information to bit 7 and then outputs the determined data. When flash memory
terminates the automatic algorithm, or bit 7 is outputting the determined data, the data of the
other bits is undefined. The data of the other bits is read during the execution of consecutive
read operations.
[bit 6]: TOGGLE (Toggle bit)
Automatic write/erase operation status
When consecutive read operations are performed during the execution of the automatic write or
erase algorithm, flash memory outputs the "1" and "0" toggle results to bit 6.
automatic write or erase algorithm ends, bit 6 stops to toggle for a consecutive read and outputs
valid data. The toggle bit becomes valid after the last write cycle of each command sequence.
If a write target sector is protected from overwriting during a write operation, the toggle bit
toggles for about 2 s and stops to toggle without overwriting. If all selected sectors are write-
protected, the toggle bit toggles for about 100 s and the system returns to the read mode
without changing data.
Temporary sector erase stop status
When a read operation is performed during a temporary sector erase stop operation, flash
memory outputs "1" if the address indicated by the address signal is included in the sector in
erase state. If the address is not included in the sector in erase state, flash memory outputs the
data of bit 6 of the read value at the address indicated by the address signal.
[bit 5] TLOVER (Time limit over)
Automatic write/erase operation status
Bit 5 indicates by becoming "1" that execution of the automatic algorithm has exceeded the time
limit (internal pulse count) specified in flash memory. In other words, when this flag outputs "1"
while the automatic algorithm is running, this indicates that a write or erase operation failed.
If an attempt is made to write to a nonblank area without erasing the data of that area, bit 5 also
indicates that the attempt failed. In this case, the data of bit 7 (data polling) is undefined, and
bit 6 (toggle bit) continues to toggle. If the time limit is exceeded in this status, bit 5 is set to "1".
Note that in this case, flash memory is not defective but is used incorrectly. If this state is
entered, perform a Reset.
[bit 3] SETIMR (Sector erase timer)
Sector erase operation status
After execution of the Sector Erase command sequence, a sector erase wait period is entered.
Bit 3 is "0" in this state and becomes "1" if the limit of the sector erase wait period is exceeded.
The data polling and toggle bits become valid after the execution of the first Ease Sector
command sequence.
366
When the
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