Fujitsu MB90460 Series, Hardware Manual, Page: 624 / 739

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CHAPTER 23 512K / 1024K BIT FLASH MEMORY
23.6.4 Deleting the Data (Sector Deletion)
This section explains the procedure of issuing the sector deletion command and
deleting any sector from the flash memory. This command enables each sector to be
deleted, and two or more sectors to be specified at the same time.
■
Deleting the data (Sector deletion)
Any sector can be deleted from the flash memory by continuously sending the sector deletion command,
listed in the command sequence table (see "23.4 Method of Starting the Automatic Algorithm in Flash
Memory"), to the target sector in the flash memory.
Method of Specifying a Sector
The sector deletion command is executed by executing the bus operation six times. The sector deletion
wait of 50
µ
s is started by writing the sector deletion code (30
H
) to any accessible even address in the target
sector in the 6th-cycle bus operation. To delete two or more sectors, the deletion code (30
H
) should be
written to the address in the target sector just after the above operation.
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Notes on Specifying Two or More Sectors
The deletion operation is started after the last sector deletion code is written and the sector deletion wait
period of 50
µ
s is terminated. Thus, the next deletion sector address and deletion code (i.e. in the 6th cycle
of the command sequence) must be input each within 50
µ
s to delete two or more sectors simultaneously,
which may not be accepted later than 50
µ
s. It can be checked whether the succeeding sector deletion code
write operation is valid, using the sector deletion timer flag (DQ3). In this case, the address from which the
sector deletion timer flag (DQ3) is read must indicate the sector to be deleted.
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Procedure of Deleting a Sector
Using the hardware sequence flag (see "23.5 Verifying Automatic Algorithm Execution Status"), the status
of the automatic algorithm within the flash memory can be determined. Figure 23.6-2 shows an example of
procedure of deleting the sector from the flash memory. Here, the toggle bit flag (DQ6) is used for
verifying the end of writing. Note that data to be used for checking the flag is read from the sector to be
deleted.
The toggle bit flag (DQ6) stops the toggle operation at the same time when the time limit exceeded flag
(DQ5) is changed to "1", so the toggle bit flag (DQ6) must be rechecked even if the time limit exceeded
flag (DQ5) is "1".
Similarly, the data polling flag (DQ7) is changed at the same time when the time limit exceeded flag (DQ5)
is changed, so the data polling flag (DQ7) must be rechecked.