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CHAPTER 22 DUAL OPERATION FLASH MEMORY
22.7 Details of Programming/Erasing Flash Memory
22.7.4
Erasing Any Data in Flash Memory (Sector Erasing)
This section explains the procedure for inputting the sector erase command to erase
any data in flash memory. Sector-by-sector erasing is enabled and multiple sectors can
be specified at the same time.
■ Erasing Any Data in Flash Memory (Sector Erasing)
Any sector in flash memory can be erased by continuously transmitting the sector erase command in the
command sequence table from CPU to flash memory.
●
How to specify sector
• The sector erase command is executed in six bus operations. By setting the address on the sixth cycle on
the even address in the target sector and programming the sector erase code (30
50 μs sector erasing wait is started
• When erasing more than one sector, the sector erase code (30
be erased, following the above.
●
Notes on specifying multiple sectors
• Sector erasing is started after a minimum 50 μs period waiting for sector erasing is completed after the
last sector erase code has been programmed.
• That is, when erasing more than one sector simultaneously, the address of erase sector address and the
sector code must be input within 50 μs. If the sector erase code is input 50 μs or later, it cannot be
accepted because a period waiting for sector erasing is completed.
• Whether continuous programming of the sector erase code is enabled can be checked by the sector erase
timer flag (DQ3).
• In this case, the address from which the sector erase timer flag (DQ3) is read should correspond to the
sector to be erased.
■ Erasing Procedure for Flash Memory Sectors
• The state of the automatic algorithm in the flash memory can be determined using the hardware
sequence flag. Figure 22.7-2 gives an example of the flash memory sector erase procedure. In this
example, the toggle bit flag (DQ6) is used to check that erase ends.
• DQ6 terminates toggling concurrently with the change of the timing limit over flag (DQ5) to "1", so the
DQ6 must be checked even when DQ5 is "1".
• Similarly, the data polling flag (DQ7) changes concurrently with the transition of the DQ5, so DQ7
must be checked.
■ Note on Sector Erasing
If the hardware reset is generated during erase operation, the data of flash memory is not guaranteed. Please
re-try sector erase.
506
FUJITSU MICROELECTRONICS LIMITED
MB90335 Series
) to data, a minimum
H
) is programmed to the sector address to
H
CM44-10137-6E
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