D12320VF25V Datasheet, PDF (630/1146 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

Section 17 ROM
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. When the program is located in external memory, an instruction for
programming the flash memory and the following instruction should be located in on-chip RAM.
Figure 17.14 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 17.12,
Flash Memory Programming and Erasing Precautions.
Figure 17.14 User Program Mode Execution Procedure
Rev.7.00 Feb. 14, 2007 page 596 of 1108
REJ09B0089-0700