H8S2639 Datasheet, PDF (951/1547 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip Microcomputer H8S Family/H8S/2600 Series

Section 21C ROM (H8S/2635 Group)
To select user program mode, select a mode that enables the on-chip flash memory (mode 6 or 7),
and apply a high level to the FWE pin. In this mode, on-chip supporting modules other than flash
memory operate as they normally would in modes 6 and 7.
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. If the program is to be located in external memory, the instruction for
writing to flash memory, and the following instruction, should be placed in on-chip RAM.
Figure 21C-10 shows the procedure for executing the program/erase control program when
transferred to on-chip RAM.
Write the FWE assessment program and
transfer program (and the program/erase
control program if necessary) beforehand
MD2, MD1, MD0 = 110, 111
Reset-start
Transfer program/erase control
program to RAM
Branch to program/erase control
program in RAM area
FWE = high*
Execute program/erase control
program (flash memory rewriting)
Clear FWE*
Branch to flash memory application
program
Notes: 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 21B.15,
Flash Memory Programming and Erasing Precautions.
Figure 21C-10 User Program Mode Execution Procedure
Rev. 6.00 Feb 22, 2005 page 891 of 1484
REJ09B0103-0600