Renesas Hitachi H8S/2191, Hardware Manual, Page: 171 / 1065

Rev. 2.0, 11/00, page 144 of 1037
7.4.2 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 means of FWE control and supply of
programming data, and storing a program/erase control program in part of the program area as
necessary.
In this mode, the chip starts up in mode 1 and applies a high level to the FWE pin.
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 7.11 shows the procedure for executing the program/erase control program when
transferred to on-chip RAM.
Clear FWE
*
FWE = high
*
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
MD0 = 1
Reset start
Write the FWE assessment program and
transfer program (and the program/erase
control program if necessary) beforehand
Note: Do not apply a constant high level to the FWE pin. Apply a high level to the FWE pin only
when the flash memory is programmed or erased. Also, while a high level is applied to the
FWE pin, the watchdog timer should be activated to prevent overprogramming or
overerasing due to program runaway, etc.
* For further information on FWE application and disconnection, see section 7.9, Flash
Memory Programming and Erasing Precautions.
Figure 7.11 User Program Mode Execution Procedure