Fujitsu FR81S User Manual
CHAPTER 45: FLASH MEMORY
5. Operation
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER : FLASH MEMORY
FUJITSU SEMICONDUCTOR CONFIDENTIAL
32
Chip Erase Command
If the chip erase command is sent to the target sector six times in a row, all sectors of the flash memory can
be erased in one step. Once the sixth write has finished, the automatic algorithm starts and the chip erase
operation is started. When the automatic erase algorithm is started, "0" is written to all of the cells in the
flash memory chip before erasing the entire chip, and there is no need to write to flash memory before the
chip erases to verify the margins (preprogramming). Furthermore, while verifying the margin, there is no
need to control the flash memory externally.
See "5.6. Chip Erase Command" for details on the actual operation.
Sector Erase Command
If the sector erase command is sent to the target sector six times in a row, the sector of the flash memory is
erased. When 40μs elapses (timeout period) after the sixth write has finished, the automatic algorithm starts
and the sector erase operation is started. If you want to erase multiple sectors, write the erase code (30
H
) to
the address of the sector to erase within the 40μs (timeout period). If the next sector is not input within the
timeout period, the sector erase command may become invalid. When the automatic erase algorithm is
started, "0" is written to the cells in the sector to erase in flash memory before erasing the sector, and there
is no need to write to flash memory before erasing the sector to verify the margins (preprogramming).
Furthermore, while verifying the margin, there is no need to control the flash memory externally.
See "5.7. Sector Erase Command" for details on the actual operation.
Note:
When security is ON, there are restrictions in the procedure for erasing the sector of the flash. See "5.9.4.
Flash Access Restrictions When Security is ON" for details.
Sector Erase Suspend Command
It is possible to shift to the sector erase suspend condition (state of the sector erase suspension) by sending
the sector erase suspend command in the command time-out or while executing the sector erase.
In the sector erase suspend condition, the reading operation of the memory cell of the sector that is not the
erase target becomes possible. However, a new neither writing nor erase command is accepted.
To restart the interrupting erase operation from the sector erase suspend condition, the erase restart
command is sent.
When the erase resume command is accepted, the state comes back to the sector erase condition, resuming
the erase operation.
It does not change to the state of the command time-out when the erase resume command is normally
written even if it is time when it changes from the state of the command time-out in this state, it changes to
the state of the erase deletion, and the sector erase operation is restarted at once.
See "5.8 Sector Erase Suspend Command" for actual operation.
Notes:
⋅
16.7μs or less is required until the sector erase operation is stopped from the issue of the sector erase
suspend command and reading from the sector that is not the erase target becomes possible.
⋅
Whether it entered the state that can be read is confirmed with the FRDY bit of the flash status register
(FSTR) or TOGG1 of the hardware sequence flag.
MB91520 Series
MN705-00010-1v0-E
1953