Boot Mode - Renesas H8S Series Hardware Manual

On-Board Programming Modes

• Boot mode

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.
H8S/2357 Group chip
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.
H8S/2357 Group chip
Boot program
Flash memory
Flash memory
Host
Programming control
program
New application
program
SCI
RAM
Host
New application
program
SCI
RAM
Boot program area
Programming control
program
erase
Figure 19-9 Boot Mode
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.
Host
New application
program
H8S/2357 Group chip
Boot program
Flash memory
Boot program area
Application program
Programming control
(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
H8S/2357 Group chip
Boot program
Flash memory
Boot program area
New application
Programming control
program
Rev.6.00 Oct.28.2004 page 577 of 1016
SCI
RAM
program
SCI
RAM
program
Program execution state
REJ09B0138-0600H