R8C datasheet(180/199 Pages) RENESAS

180 / 199 page

R8C/10 Group

19. Usage Notes

Rev.1.20 Jan 27, 2006

page 170 of 180

REJ09B0019-0120

19.7 Flash Memory Version

19.7.1 CPU Rewrite Mode

q Operation Speed

Before entering CPU rewrite mode (EW0 mode, EW1 mode), select 5MHz or below for the CPU clock

using the CM06 bit in the CM0 register and the CM16 to CM17 bits in the CM1 register.

q Instructions Diabled Against Use

The following instructions cannot be used in EW0 mode because the flash memory internal data is

referenced: UND, INTO and BRK instructions.

q How to Access

Write “0” to the corresponding bits before writing “1” when setting the FMR01, FMR02, and FMR11

bits to ”1”. Do not generate an interrupt between writing “0” and “1”.

q Rewriting User ROM Area

In EW0 mode, if the power supply voltage drops while rewriting any block in which the rewrite control

program is stored, the flash memory may not be able to be rewritten because the rewrite control

program cannot be rewritten correctly. In this case, use stnadard serial I/O mode.

q Reset Flash Memory

Since the CPU stops and cannot return when setting the FMSTP bit in the FMR0 register to “1” (flash

memory stops) during erase suspend in EW1 mode, do not set the FMSTP bit to “1”.

q Entering Stop Mode or Wait Mode

Do not enter stop mode or wait mode during erase-suspend.

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