SH7018 Datasheet, PDF (334/431 Pages) Renesas Technology Corp – SuperH™ RISC engine

;;^{16.2.3 On-BoardProgrammingModes}
Boot Mode
Figure 16.3 illustrates overwrite operation in the boot mode. For more information on the boot
mode, see 16.6.1, 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
SH7018
Boot program
Flash memory
SCI1
RAM
Application program
(old version)
2. Programming control program transfer
When boot mode is entered, the boot program in
the SH7018 (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
SH7018
Boot program
Flash memory
SCI1
RAM
Programming control
program
Application program
(old version)
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.
Host
New application
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
SH7018
Boot program
Flash memory
SCI1
RAM
Programming control
program
SH7018
Boot program
Flash memory
SCI1
RAM
Programming control
program
Flash memory
erase
Boot program area
New application
program
Boot program area
Program execution state
Figure 16.3 Overwrite Operation in the Boot Mode
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