Sector Erase Timer Flag (Dq3) - Fujitsu MB90480 Series Hardware Manual

23.5.4 Sector Erase Timer Flag (DQ3)

The sector erase timer flag (DQ3) indicates whether the device is waiting for the end of
sector erase after starting of the sector erase command.
■
State transitions of sector erase timer flag (DQ3)
❍ State changes during normal operation
Write
Operation
→
operation
state
completed
→
DQ3 0 DATA: 3
❍ State changes in operation error mode
Operation Write
state operation
DQ3 0
■
Sector erase operation
In read accesses after the sector erase command starts, the flash memory outputs "0" if the
sector erase waiting time is in progress, irrespective of the address specified by the address
signal for the sector that issued the command, or it outputs "1" if the sector erase waiting time
was exceeded.
If the data polling function or toggle bit function shows that the erase algorithm is being
executed and this flag is set to "1", erasure under internal control will start. Subsequent
commands other than writing the sector erase code or erase suspend are ignored until the
erasure is completed.
If this flag is set to "0", the flash memory will accept writing of the additional sector erase code.
Fujitsu recommends checking the state of the flag before subsequent sector erase codes are
written to verify the operational state of the device. If a second state check returns the flag to
"1", the erase code for an additional sector may not have been accepted.
■
Sector erase suspend
If read access is performed when a sector erase operation is suspended, the flash memory
outputs "1" for an address of a sector being erased. Otherwise, the read value of bit3 (DATA: 3)
for the corresponding address will be output.
Chip sector Sector
→
erase wait
erase
→
start
completed
→
1 0 1
Chip sector
erase
operation
1
CHAPTER 23 2M/3M BIT FLASH MEMORY
Sector erase
→
Sector erase
suspend
erase suspend
resume
(sector being
(sector being
erased)
erased)
→
1 0 0
Sector erased
→
Suspend mode
Sector not being
erased
→
1 DATA: 3
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