Data Erasure (Sector Erasure) - Fujitsu FR60 Hardware Manual

CHAPTER 17 FLASH MEMORY
17.5.4

Data Erasure (Sector Erasure)

This section explains how to issue sector erase commands to erase specified sectors in
flash memory. Erasure in sector units is possible and two or more sectors can be
specified with this command.
Specified sectors can be erased from flash memory by continuously sending sector
erase commands (listed in the command sequence table) to the sectors in the flash
memory.
■ How to Specify Sectors
A sector erase operation can be performed with six bus operations. A 50-µs sector erase wait period starts
when a sector erase code (30
sixth cycle. To erase another sector, a sector code (30
■ Note on Specifying Two or More Sectors
A sector erase operation starts when the 50 µs sector erase wait period terminates after the final sector erase
code is written. Therefore, when two or more sectors are to be specified, the address and erase code of each
target sector must be entered within 50 µs (in the sixth cycle of the command sequence) after specifying the
preceding sector. Note that an address and erase code not entered within 50 µs may not be accepted. The
sector erase timer (hardware sequence flag: SETIMR) can be used to check the validity of a written sector
erase code. The address at which the read sector erase timer is written should indicate the target sector.
■ Sector Erase Procedure
The hardware sequence flag can be used to check the status of the automatic algorithm in flash memory.
Figure 17.5-2 shows an example of the sector erase procedure. In this example, the toggle bit flag
(TOGGLE) is used to check for termination of the erase operation.
Note that data for the flag check is read from the sector to be erased.
The toggle bit flag (TOGGLE) stops toggling simultaneously when the value of the time limit over flag
(TLOVER) changes to "1." Therefore, TOGGLE must be rechecked even though TLOVER is set to "1."
Because the data polling flag (DPOLL) also changes with TLOVER, it must also be rechecked.
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) is written to an even-numbered address accessible in the target sector in the
H
) must be written in the same cycle the same way.
H