D12320VF25V Datasheet, PDF (666/1146 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

Section 17 ROM
17.13.4 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.
Host
Programming control
program
New application
program
Chip
Boot program
Flash memory
SCI
RAM
Application program
(old version)
2. Programming control program transfer
When boot mode is entered, the boot program in
the 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
Chip
Boot program
Flash memory
Application program
(old version)
SCI
RAM
Boot program area
Programming control
program
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.
Host
New application
program
Chip
Boot program
Flash memory
Flash memory
prewrite-erase
SCI
RAM
Boot program area
Programming control
program
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
Chip
Boot program
Flash memory
New application
program
SCI
RAM
Boot program area
Programming control
program
Figure 17.35 Boot Mode
Rev.7.00 Feb. 14, 2007 page 632 of 1108
REJ09B0089-0700
Program execution state