Timing Limit Exceeded Flag (Dq5) - Fujitsu MB90390 Series Hardware Manual

CHAPTER 28 3M-BIT FLASH MEMORY
28.6.3

Timing Limit Exceeded Flag (DQ5)

The timing limit exceeded flag (DQ5) is used to post that execution of the automatic
algorithm has exceeded the time (internal pulse count) prescribed in the flash memory.
■ Timing Limit Exceeded Flag (DQ5)
Table 28.6-7 lists the timing limit exceeded flag state transitions (state change for normal operation) and
Table 28.6-8 lists the timing limit exceeded flag state transitions (state change for abnormal operation).
Table 28.6-7 Timing Limit Exceeded Flag State Transitions (State Change for Normal Operation)
Write →
Operating
state Completed
0 →
DQ5
DATA:5
Table 28.6-8 Timing Limit Exceeded Bit Flag State Transitions (State Change for Abnormal
Operating state
●
Write/chip sector erase
Read-access after write or chip/sector erase automatic algorithm activation causes the flash memory to
output "0" if the time is within the prescribed time (time required for write/erase) or to output "1" if the
prescribed time has been exceeded. Because this is done regardless of whether the automatic algorithm is
being executed or has terminated, it is possible to determine whether write/erase was successful or
unsuccessful. That is, when this flag outputs "1", writing can be determined to have been unsuccessful if
the automatic algorithm is still being executed by the data polling function or toggle bit function.
For example, writing "1" to a flash memory address where "0" has been written will cause the fail state to
occur. In this case, the flash memory will lock and execution of the automatic algorithm will not terminate.
As a result, valid data will not be output from the data polling flag (DQ7). In addition, the toggle bit flag
(DQ6) will exceed the time limit without stopping the toggle operation and the timing limit exceeded flag
(DQ5) will output "1". Note that this state indicates that the flash memory is not faulty, but has been used
correctly. When this state occurs, execute the Reset command.
570
Chip/sector Sector
erase →
erase wait
→ Started
Completed
0 → 1
Operation)
Write
DQ5 1
Sector erase
→ Erase
suspend
(sector being
erased)
0 0
Chip/sector erase
1
Sector erase
Sector erase
suspend →
suspended
Restarted
(sector not
(sector being
being erased)
erased)
0 DATA:5