Writing Data To Flash Memory - Fujitsu MB90480 Series Hardware Manual

CHAPTER 23 2M/3M BIT FLASH MEMORY

23.6.2 Writing Data to Flash Memory

This section describes the procedures for issuing a write command to write data to the
flash memory.
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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 23.4-1) 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 be started.
❍ 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
Data polling flag (DQ7) or toggle bit flag (DQ6) doesn't enter the state of the end if data in the
flash memory is written from "0" in "1". So, it is judged that the flash memory element is
defective, and falls into the following states. Therefore, please do not return data in the flash
memory from "0" to "1" by write.
• Time limit over flag (DQ5) becomes the error state by exceeding the write regulation time.
• In the appearance, it becomes the state that "1" seems to be written in data on the flash
memory. (Data is "0" when read the data at read/reset state. Please erase it when you return
data from "0" to "1".)
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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