Writing Data To Flash Memory - Fujitsu F2MC-16LX Hardware Manual

26.6.2 Writing Data to Flash Memory

This section describes the procedures for issuing a write command to write data to the
flash memory.
I Writing data to flash memory
To start the automatic data write algorithm for the flash memory, repeatedly send the write
command in the command sequence table (see Table 26.4-1 "Command sequence table") to
the relevant sector in the flash memory. When data writing to the target address is completed in
the 4th cycle, the automatic algorithm, and therefore automatic writing, will start.
❍ Address specification method
Only an even write address can be specified in the write data cycle. Specifying an odd address
will cause a failure during writing. It is necessary to write to even addresses in word units.
Any order of addresses or even addresses exceeding the sector boundary are acceptable in
write operations. However, a single write command can only write one word of data.
❍ Notes on writing data
An already written item of data cannot be overwritten by another item in a writing operation.
When an item of data is overwritten, the data polling algorithm (DQ7) or toggle operation (DQ6)
will not end and the flash memory element will be judged to be defective. Consequently, the
specified time for writing will be exceeded, and either the timing limit excess flag (DQ6) will
indicate an error, or it will falsely appear as if overwriting had been successful, but subsequent
read operations in the read/reset state will nevertheless return the original value. A data item
can only be overwritten by performing a erase operation in between.
During execution of automatic write, all other commands are ignored. Note that if a hardware
reset starts while a write operation is in progress, the data that is written to the address is not
assured.
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