R8CSLASH2G datasheet(268/344 Pages) RENESAS

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R8C/2G Group

20. Flash Memory

Rev.1.00

Apr 04, 2008

Page 248 of 318

REJ09B0387-0100

20.4

CPU Rewrite Mode

In CPU rewrite mode, the user ROM area can be rewritten by executing software commands from the CPU.

Therefore, the user ROM area can be rewritten directly while the MCU is mounted on a board without using a

ROM programmer. Execute the software command only to blocks in the user ROM area.

Table 20.3 lists the Differences between EW0 Mode and EW1 Mode.

Table 20.3

Differences between EW0 Mode and EW1 Mode

Item

EW0 Mode

EW1 Mode

Operating mode

Single-chip mode

Areas in which a rewrite

control program can be

executed

RAM (Rewrite control program is

executed after being transferred)

User ROM or RAM

Areas which can be

rewritten

User ROM

However, blocks which contain a rewrite

control program are excluded

Software command

restrictions

None

• Program and block erase commands

Cannot be run on any block which

contains a rewrite control program

• Read status register command

Cannot be executed

Modes after program or

erase

Read status register mode

Read array mode

Modes after read status

Read status register mode

Do not execute this command

CPU status during auto-

write and auto-erase

Operating

Hold state (I/O ports hold state before the

command is executed)

Flash memory status

detection

• Read bits FMR00, FMR06, and FMR07

in the FMR0 register by a program

• Execute the read status register

command and read bits SR7, SR5, and

SR4 in the status register.

Read bits FMR00, FMR06, and FMR07 in

the FMR0 register by a program

CPU clock

5 MHz or below

No restriction (on clock frequency to be

used)

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