HD64F2149 Datasheet, PDF (712/1035 Pages) Renesas Technology Corp – Hitachi 16-Bit Single-Chip Microcomputer

22.6.2 User Program Mode
When set to user program mode, the chip can program and erase its flash memory by executing a
user program/erase control program. Therefore, on-board reprogramming of the on-chip flash
memory can be carried out by providing an on-board means of supplying programming data, and
storing a program/erase control program in part of the program area as necessary.
To select user program mode, select a mode that enables the on-chip flash memory (mode 2 or 3).
In this mode, on-chip supporting modules other than flash memory operate as they normally
would in mode 2 and 3.
The flash memory itself cannot be read while the SWE bit is set to 1 to perform programming or
erasing, so the control program that performs programming and erasing should be run in on-chip
RAM or external memory.
Figure 22.11 shows the procedure for executing the program/erase control program when
transferred to on-chip RAM.
Write the transfer program
(and the program/erase control program
if necessary) beforehand
MD1, MD0 = 10, 11
Reset-start
Transfer program/erase control
program to RAM
Branch to program/erase control
program in RAM area
Execute program/erase control
program (flash memory rewriting)
Branch to flash memory application
program
Note: The watchdog timer should be activated to prevent overprogramming or overerasing
due to program runaway, etc.
Figure 22.11 User Program Mode Execution Procedure
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