Data Writing - Fujitsu FR60 Hardware Manual

17.5.2

Data Writing

This section explains how to issue a write command to write data to flash memory.
■ Writing Data to Flash Memory
The automatic data write algorithm can be started by continuously sending write commands (listed in the
command sequence table) to target sectors in flash memory.
The automatic algorithm and automatic writing start when writing data to the target address terminates in
the fourth cycle.
■ How to Specify Address
Data can be written by freely specifying the order of addresses where data is to be written. Moreover, data
can be written beyond sector boundaries. Note that items of data can only be written with each write
command in units of half-words.
■ Notes on Writing Data
Data "0" cannot be changed to "1" in a write operation. If data "1" is overwritten, the data polling algorithm
or toggle operation does not terminate, and the flash memory device is considered defective. An error is
assumed with the time limit over flag if the specified write time is exceeded, or if only data "1" is
apparently written, although data "0" is read in read/reset status. Data "0" can be changed to "1" only with
an erase operation. All commands are ignored during automatic writing. If a hardware reset is activated
during writing, the data being written is not guaranteed.
■ Write Procedure
Figure 17.5-1 shows an example of the write procedure.
The status of the automatic algorithm in flash memory can be checked using the hardware sequence flag. In
the example in Figure 17.5-1 , the data polling flag (DPOLL) is used to check for termination of the write
operation.
Data for the flag check is read from the address where the last data was written.
The data polling flag (DPOLL) changes together with the time limit over flag (TLOVER). Therefore,
DPOLL must be rechecked even though TLOVER is set to "1."
The toggle bit flag (TOGGLE) also stops toggling simultaneously when the value of TLOVER is changed
to "1." Therefore, this flag must also be rechecked.
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