H8S2148 Datasheet, PDF (751/1177 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip Microcomputer H8S Family/H8S/2100 Series

Section 23 ROM (H8S/2148 F-ZTAT A-Mask Version, H8S/2147 F-ZTAT A-Mask Version, H8S/2144 F-ZTAT A-Mask Version)
23.6.2 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 23.11 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 23.11 User Program Mode Execution Procedure
Rev. 4.00 Sep 27, 2006 page 707 of 1130
REJ09B0327-0400