Hitachi H8S/2378, H8S/2378R Series Hardware Manual page 812

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.
Programming control
program
New application
program
This LSI
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, entire flash
memory erasure is performed, without regard to
blocks.
New application
program
This LSI
Boot program
Flash memory
Flash memory
prewrite-erase
Rev. 1.0, 09/01, page 768 of 904
Host
SCI
RAM
Host
SCI
RAM
Boot program area
Programming control
program
Figure 20.3 Boot Mode
2. Programming control program transfer
When boot mode is entered, the boot program in
the chip (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
This LSI
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
This LSI
Boot program
Flash memory
New application
program
SCI
RAM
Boot program area
Programming control
program
SCI
RAM
Boot program area
Programming control
program
Program execution state