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On-Board Programming Modes
• Boot Mode
1.
Initial state
The flash memory is in the erased state when shipped.
The procedure for rewriting an old version of an
application program or data is described here. The
user should prepare a programming control program
and the new application program beforehand in the
host.
Programming
control program
New application
H8/3857F or H8/3854F
Boot program
Flash memory
Application
program
(old version)
3. Flash memory initialization
The erase program in the boot program area (in RAM)
is executed, and the flash memory is initialized (to
H'FF). In boot mode, total flash memory erasure is
performed, without regard to blocks.
Programming
control program
New application
H8/3857F or H8/3854F
Boot program
Flash memory
Flash memory erase
Host
program
SCI
(RAM)
Host
program
SCI
(RAM)
Boot program area
Figure 6.4 Boot Mode
2. Programming control program transfer
When boot mode is entered, the boot program in the
chip (already incorporated in the chip) is started, an
SCI communication check is carried out, and the boot
program required for flash memory erasing is
automatically transferred to the RAM boot program
area.
Host
Programming
control program
New application
program
H8/3857F or H8/3854F
Boot program
Flash memory
Application
program
(old version)
4. Writing new application program
The programming control program in the host is
transferred to RAM by SCI communication and
executed, and the new application program in the host
is written into the flash memory.
Host
H8/3857F or H8/3854F
Boot program
Flash memory
New application
program
Program execution state
Rev.3.00 Jul. 19, 2007 page 123 of 532
6. ROM
SCI
(RAM)
Boot program area
SCI
(RAM)
Programming
control program
REJ09B0397-0300
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