Datasheet

Section 22 ROM (H8S/2138 F-ZTAT A-Mask Version, H8S/2134 F-ZTAT A-Mask Version)
Rev. 4.00 Jun 06, 2006 page 629 of 1004
REJ09B0301-0400
On-Board Programming Modes
• Boot mode
Flash memory
The chip
RAM
Host
Programming control
program
SCI
Application program
(old version)
Programming control
program
New application
program
New application
program
Flash memory
The chip
RAM
Host
SCI
Application program
(old version)
Boot program area
Programming control
program
New application
program
Flash memory
The chip
RAM
Host
SCI
Flash memory
erase
Boot program
Flash memory
The 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. Programming control program transfer
When boot mode is entered, the boot program in
the 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 programBoot program
Boot program area
Programming control
program
Boot program
area
Programming
control program
Figure 22.4 Boot Mode