
501
On-Board Programming Modes
Boot Mode
Flash memory
H8/3337SF
RAM
Host
On-board update routine
SCI
Application
program
(old version)
;;
New application
program
Flash memory
H8/3337SF
RAM
Host
SCI
Application
program
(old version)
New application
program
Flash memory
H8/3337SF
RAM
Host
SCI
Flash memory
erase
Boot program
New application
program
Flash memory
H8/3337SF
:
Program execution state
RAM
Host
SCI
New application
program
Boot program
Boot program area
On-board update routine
;
On-board update routine
;
On-board update
routine
Boot program area
Boot program
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 an
on-board update routine and the new
application program beforehand in the host.
2. SCI communication check
When boot mode is entered, the boot program
in the H8/3337SF (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.
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.
4. Writing new application program
The on-board update routine in the host to
RAM is transferred to RAM by SCI
communication and executed, and the new
application program in the host is written into
the flash memory.
Figure 21.3 Boot Mode