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6. ROM
• User Program Mode
1. Initial state
The FWE assessment program that confirms that a high
level has been applied to the FWE pin, and the program
that will transfer the programming/erase control program
from flash memory to on-chip RAM, should be written into
the flash memory by the user beforehand. The
programming/erase control program should be prepared
in the host or in the flash memory.
Host
Programming/erase
control program
New application
program
H8/3857F or H8/3854F
Boot program
Flash memory
FWE assessment
program
Transfer program
Application program
(old version)
3. Flash memory initialization
The programming/erase program in RAM is executed, and
the flash memory is initialized (to H'FF). Erasing can be
performed in block units, but not in byte units.
Host
New application
program
H8/3857F or H8/3854F
Boot program
Flash memory
FWE assessment
program
Transfer program
Flash memory
erase
Rev.3.00 Jul. 19, 2007 page 124 of 532
REJ09B0397-0300
SCI
(RAM)
SCI
(RAM)
Programming/erase
control program
Figure 6.5 User Program Mode (Example)
2. Programming/erase control program transfer
When a high level is applied to the FWE pin, user
software confirms this fact, executes the transfer program
in the flash memory, and transfers the programming/erase
control program to RAM.
Host
New application
program
H8/3857F or H8/3854F
Boot program
Flash memory
FWE assessment
program
Transfer program
Application program
(old version)
4. Writing new application program
Next, the new application program in the host is written
into the erased flash memory blocks. Do not write to
unerased blocks.
Host
H8/3857F or H8/3854F
Boot program
Flash memory
FWE assessment
program
Transfer program
New application
program
SCI
(RAM)
Programming/erase
control program
SCI
(RAM)
Programming/erase
control program
Program execution state
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