Figure 24.3 Boot Mode - Renesas H8S/2158 User Manual

Section 24 ROM
1. Initial state
The flash memory is erased at shipment.
The following describes how to write over
an old-version application program or data 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
<This LSI>
Boot program
<Flash memory>
Application
program
(old version)
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, total flash
memory erasure is performed, without regard to
blocks.
<Host>
New
application program
<This LSI>
Boot program
<Flash memory>
Flash memory
erase
Rev. 3.00 Jan 25, 2006 page 720 of 872
REJ09B0286-0300
SCI
<RAM>
SCI
<RAM>
Boot program area
Programming
control program

Figure 24.3 Boot Mode

2. SCI communication check
When boot mode is entered, the boot program in
this LSI (originally incorporated in the chip) is started
and SCI communication is checked. Then the boot
program required for flash memory erasing is
automatically transferred to the RAM boot program
area.
<Host>
New
application program
<This LSI>
Boot program
<Flash memory>
Boot program area
Application
program
(old version)
4. Writing new application program
The programming control program transferred from
the host to RAM via SCI communication is executed,
and the new application program in the host is written
into the flash memory.
<Host>
<This LSI>
Boot program
<Flash memory>
Boot program area
New
application
program
SCI
<RAM>
Programming
control program
SCI
<RAM>
Programming
control program
Program execution state