569
On-Board Programming Modes
Boot mode
Flash memory
H8S/2138 or H8S/2134 Series chip
RAM
Host
Programming control
program
SCI
Application program
(old version)
Programming control
program
New application
program
Programming control
program
New application
program
Flash memory
H8S/2138 or H8S/2134 Series chip
RAM
Host
SCI
Application program
(old version)
Boot program area
New application
program
Flash memory
H8S/2138 or H8S/2134 Series chip
RAM
Host
SCI
Flash memory
erase
Boot program
Flash memory
H8S/2138 or H8S/2134 Series chip
Program execution state
RAM
Host
SCI
New application
program
Boot program
1. Initial state
The flash memory is in the erased state when the
device is shipped. The description here applies to
the case where the old program version or data
is being rewritten. The user should prepare the
programming control program and new
application program beforehand in the host.
2. SCI communication check
When boot mode is entered, the boot program in
the H8S/2138 or H8S/2134 Series chip (originally
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, 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 by SCI communication is
executed, and the new application program in the
host is written into the flash memory.
Boot program
Boot program area
Programming
control program
Figure 21.4 Boot Mode