Datasheet

Rev.6.00 Oct.28.2004 page 577 of 1016
REJ09B0138-0600H
On-Board Programming Modes
• Boot mode
Flash memory
H8S/2357 Group chip
RAM
Host
Programming control
program
SCI
Application program
(old version)
Application program
(old version)
New application
program
Flash memory
H8S/2357 Group chip
RAM
Host
SCI
Boot program area
New application
program
Flash memory
H8S/2357 Group chip
RAM
Host
SCI
Flash memory
erase
Boot program
New application
program
Flash memory
H8S/2357 Group chip
Program execution state
RAM
Host
SCI
New application
program
Boot program
Programming control
program
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.
2. Programming control program transfer
When boot mode is entered, the boot program in
the H8S/2357 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.
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.
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.
Programming control
program
Boot programBoot program
Boot program area Boot program area
Programming control
program
Figure 19-9 Boot Mode