SH7040 Datasheet, PDF (722/923 Pages) Renesas Technology Corp – Renesas 32-Bit Single-Chip RISC Microprocessor SuperH RISC engine Family/SH7040 Series(CPU Core SH-2)

22.2.3 Onboard Program Mode
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
Program
New application
program
LSI
Boot program
Flash memory
Application
version
(old version)
SCI1
RAM
2. Programming control program transfer
When boot mode is entered, the boot program in
the LSI (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
LSI
Boot program
Flash memory
SCI1
RAM
Program
Application
Boot program area
version
(old version)
3. Initializing the flash memory
To initialize (to H'FF) the flash memory, execute
the erase program located in the boot program
area (within RAM). During the boot mode, the
entire flash memory is erased, regardless of blocks.
HOST
4. Writing the new application program
Execute the program transferred to RAM from the
host and write the new application program located
at the transfer destination to the flash memory.
HOST
New application
program
LSI
;; ^{Boot program}
Flash memory
Erasing the
flash memory
SCI1
RAM
Program
Boot program area
LSI
Boot program
Flash memory
;; _{New application}
program
SCI1
RAM
Program
Boot program area
;;;_{Program execution state}
Figure 22.3 Boot Mode
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