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1. Initial state
The old program version or data remains written
in the flash memory. The user should prepare the
programming control program and new
application program beforehand in the host.
Host
Programming control
program
New application
program
H8/3664
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, the entire flash
memory area is erased, without regard to blocks.
Host
New application
program
H8/3664
Boot program
Flash memory
Flash memory
erase
SCI3
RAM
SCI3
RAM
Boot program area
Programming control
program
Figure 7.3 Boot Mode
2. Programming control program transfer
When boot mode is entered, the boot program in
the H8/3664 (originally incorporated in the chip)
is started and the programming control program
in the host is transferred to RAM via SCI
communication. The boot program required for
flash memory erasing is automatically transferred
to the RAM boot program area.
Host
New application
program
H8/3664
Boot program
Flash memory
Application program
(old version)
4. Writing new application program
The programming control program transferred
from the host to RAM is executed, and the new
application program in the host is written into the
flash memory.
Host
H8/3664
Boot program
Flash memory
New application
program
SCI3
RAM
Boot program area
Programming control
program
SCI3
RAM
Boot program area
Programming control
program
Program execution state
101
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