Datasheet
684
22.2.3 Onboard Program Mode
Boot mode
New application
program
New application
program
New application
program
Program
Program
ProgramProgram
LSI LSI
Boot program Boot program
LSI LSI
Boot program
Flash memory
Application
version
(old version)
Boot program
Flash memory Flash memory
Application
version
(old version)
RAM Flash memory RAM
RAM RAM
SCI1 SCI1
SCI1 SCI1
HOSTHOST
HOSTHOST
Boot program area
Boot program areaBoot program area
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.
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.
Erasing the
flash memory
New application
program
Program execution state
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.
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.
Figure 22.3 Boot Mode