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25.7.3 All Data Erasing from Flash Memory (Chip Erasing)
This section explains the procedure for issuing the chip erase command to erase all data from flash memory.
n All data erasing from flash memory (Chip Erase)
All data can be erased from flash memory by continuously sending the chip erase command in the command
sequence table (see Table 25-2 of Section 25.5) to a target sector in flash memory.
The chip erase command is executed in six bus operations. Chip erasing is started at completion of the 6th
write cycle. Before chip erasing, the user need not perform writing to flash memory. During execution of the
automatic erasing algorithm, flash memory writes 0 for verification before automatically erasing all cells.
25.7.4 Erasing any Data in Flash Memory (Sector Erasing)
This section explains the procedure for issuing the Sector Erase command to erase any data in flash
memory. Sector-by-sector erasing is enabled and multiple sectors can be specified at a time.
n Erasing any data in flash memory (sector erasing)
Any sector in flash memory can be erased by continuously sending the Sector Erase command in the
command sequence table (see Table 25-2 of Section 25.5) to a target sector in flash memory.
• Specifying sector
The sector erase command is executed in six bus operations. When the sector erase code (30
to any one of the accessible even addresses in the sixth cycle, a 50-µs sector erasing wait is started.
When erasing more than one sector, the sector erase code (30
the above sequence.
• Precautions at specifying multiple sectors
Sector erasing is started after a 50-µs period waiting for sector erasing is completed after the last sector
erase code has been written. That is, when erasing more than one sector simultaneously, the next sector
to be erased must be input within 50 µs and subsequent sectors many not be accepted.
subsequent writing of the sector erase code is enabled can be checked by the sector erase timer (the
hardware sequence flag (DQ3)). In this case, the address from which the sector erase timer is read should
correspond to the sector to be erased.
n Erasing procedure for flash memory sectors
The state of the automatic algorithm in the flash memory can be determined using the hardware sequence
flag (Section 25.6). Figure 25.4 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.
Note that data to be read to check the flag is read from the sector about to be erased.
The toggle bit flag (DQ6) stops the toggle operation concurrently with the transition of the timing limit
exceeding flag (DQ5) to 1, so the toggle bit flag (DQ6) must be re-checked even when DQ5 is 1.
Similarly, the data polling flag (DQ7) changes concurrently with the transition of the timing limit exceeding
flag (DQ5), so DQ7 must be re-checked.
1-MBIT FLASH MEMORY
25-19
) is written to the sector address, following
H
) is written
H
Whether
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