7641 datasheet(101/385 Pages) RENESAS

101 / 385 page

Rev.2.00

Aug 28, 2006

page 84 of 113

7641 Group

REJ09B0336-0200

HARDWARE

FLASH MEMORY MODE

Fig. 81 CPU rewrite mode set/release flowchart

End

Start

Execute read array command or reset flash

memory by setting flash memory reset bit (by

writing “1” and then “0” in succession) (Note 3)

Single-chip mode, Memory expansion mode or

Boot mode

Set CPU mode registers A, B (Note 2)

Using software command execute erase,

program, or other operation

Jump to control program transferred in memory

other than internal flash memory

(Subsequent operations are executed by control

program in this memory)

Transfer CPU rewrite mode control program to

memory other than internal flash memory

Notes1: When starting the MCU in the single-chip mode or memory expansion mode, supply

4.5 V to 5.25 V to the CNVss pin until checking the CPU rewrite mode entry flag.

2: Set the main clock as follows depending on the XIN divider select bit of clock control

When XIN divider select bit = “0” (

φ = f(XIN)/4), the main clock is 24 MHz or less

When XIN divider select bit = “1” (

φ = f(XIN)/2), the main clock is 12 MHz or less.

3: Before exiting the CPU rewrite mode after completing erase or program operation,

always be sure to execute the read array command or reset the flash memory.

Write “0” to CPU rewrite mode select bit

Set CPU rewrite mode select bit to “1” (by

writing “0” and then “1” in succession)

Check CPU rewrite mode entry flag

Setting

Released

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