HD64F3437TF16 Datasheet, PDF (548/752 Pages) Hitachi Semiconductor – 12 V must not be applied to the S-mask model (single-power-supply specification), as this may permanently damage the device.

21.3.2 User Programming Mode
When set to user programming mode, the H8/3437SF can erase and program its flash memory by
executing a user program. On-board updates of the on-chip flash memory can be carried out by
providing an on-board circuit for supplying programming data, and storing an update program in
part of the program area.
To select user programming mode, start up in a mode that enables the on-chip flash memory
(mode 2 or 3). In user programming mode, the on-chip supporting modules operate as they
normally would in mode 2 or 3, except for the flash memory.
The flash memory cannot be read while the SWE bit is set to 1 in order to perform programming
or erasing, so the update program must be executed in on-chip RAM or external memory.
User Programming Mode Execution Procedure (Example): Figure 21.11 shows the execution
procedure for user programming mode when the on-board update routine is executed in RAM.
The transfer program (and on-board update
program as required) is written in flash
memory ahead of time by the user.
Set MD₁ and MD₀ to 10 or 11
Start from reset
Transfer on-board update routine
into RAM
Branch to flash memory on-board
update routine in RAM
Execute flash memory on-board
update routine (update flash memory)
Branch to application program
in flash memory
Note: Start the watchdog timer to prevent over-erasing due to program runaway, etc.
Figure 21.11 User Programming Mode Operation (Example)
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