Erasing All Data (Erasing Chips) - Fujitsu F2MCTM-16LX Hardware Manual

CHAPTER 24 512K-BIT FLASH MEMORY
24.7.3

Erasing All Data (Erasing Chips)

This section describes the procedure for issuing the Chip Erase command to erase all
data in the flash memory.
Erasing all Data in the Flash Memory (Erasing chips)
All data can be erased from the flash memory by sending the Chip Erase command in the command
sequence table (see Table 24.5-1 ) continuously to the target sector in the flash memory.
The Chip Erase command is executed in six bus operations. When writing of the sixth cycle is completed,
the chip erase operation is started. For chip erase, the user need not write to the flash memory before
erasing. During execution of the automatic erase algorithm, the flash memory writes 0 for verification
before all of the cells are erased automatically.
Erasing Chip in the Flash Memory
The hardware sequence flags (see "24.6 Confirming the Automatic Algorithm Execution State") can be
used to determine the state of the automatic algorithm in the flash memory. Figure 24.7-2 is an example of
the procedure for erasing chip in the flash memory. Here, the toggle bit flag (DQ6) is used to confirm that
erasing has terminated.
The data that is read to check the flag is read from the sector to be erased.
The toggle bit flag (DQ6) stops the toggle operation at the same time that the timing limit exceeded flag
(DQ5) is changed to 1. For example, even if the timing limit exceeded flag (DQ5) is 1, the toggle bit flag
(DQ6) must be rechecked.
The data polling flag (DQ7) also changes at the same time that the timing limit exceeded flag bit (DQ5)
changes. As a result, the data polling flag (DQ7) must be rechecked.
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