R8CSLASH13 datasheet(185/224 Pages) RENESAS

185 / 224 page

R8C/13 Group

Rev.1.20

Jan 27, 2006

page 174 of 205

REJ09B0111-0120

Figure 17.8 Process to Reduce Power Consumption in On-Chip Oscillator Mode (Main Clock Stops)

Turn main clock on

Transfer a on-chip oscillator mode (main clock

stop) program to any area other the flash memory

Switch the clock source for CPU clock.

Turn XIN off

Jump to the on-chip oscillator mode (main clock

stop) program which has been transferred to any

area other the flash memory.

(The subsequent processing is executed by a

program in any area other than the flash memory.)

Wait until the flash memory circuit stabilizes

(15

µs)(3)

Set the FMSTP bit to “0” (flash memory operation)(4)

Set FMSTP bit to “1”

(flash memory stopped. Low power state)(1)

Process of on-chip oscillator mode (main

clock stop)

switch the clock source for CPU clock(2)

On-chip oscillator mode

(main clock stop) program

Write “0” to the FMR01 bit

(CPU rewrite mode disabled)

Set the FMR01 bit by writing “0” and then “1”

(CPU rewrite mode enabled)

Jump to a specified address in the flash memory

wait until oscillation stabilizes

NOTES:

1. Set the FMR01 bit to “1” (CPU rewrite mode) before setting the FMSTP bit to “1” .

2. Before the clock source for CPU clock can be changed, the clock to which to be changed must be stable.

3. Insert a 15 µs wait time in a program. Avoid accessing to the flash memory during this wait time.

4. Ensure 10 µs until setting “0” (flash memory operates) after setting the FMSTP bit to “1” (flash memory stops).

17.4 CPU Rewrite Mode

R8C/13 Datasheet(PDF) 185 Page - Renesas Technology Corp