Datasheet

Section 21 ROM (Mask ROM Version, H8S/2138 F-ZTAT, H8S/2134 F-ZTAT, and H8S/2132 F-ZTAT)
Rev. 4.00 Jun 06, 2006 page 599 of 1004
REJ09B0301-0400
21.6.2 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 on-board supply of 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 21.11 shows the procedure for executing the program/erase control program when
transferred to on-chip RAM.
Branch to flash memory application
program
Branch to program/erase control
program in RAM area
Execute program/erase control
program (flash memory rewriting)
Transfer program/erase control
program to RAM
MD1, MD0 = 10, 11
Reset-start
Write the transfer program (and the program/
erase control program if necessary) beforehand
Note: The watchdog timer should be activated to prevent overprogramming or overerasing
due to program runaway, etc.
Figure 21.11 User Program Mode Execution Procedure