Renesas R8C series

R8C/1A Group, R8C/1B Group 18. Flash Memory
Rev.1.30 Dec 08, 2006 Page 260 of 315
REJ09B0252-0130
Figure 18.11 Process to Reduce Power Consumption in On-Chip Oscillator Mode (Main Clock
Stops)
Transfer an on-chip oscillator mode (main clock stops)
program to an area other than the flash memory.
Jump to the on-chip oscillator mode (main clock stops)
program which has been transferred to an area other
than the flash memory.
(The subsequent processing is executed by the program
in an area other than the flash memory.)
Write 0 to the FMR01 bit before writing 1
(CPU rewrite mode enabled)
Switch the clock source for the CPU clock.
Turn XIN off.
Process in on-chip oscillator mode (main
clock stops)
Write 0 to the FMR01 bit
(CPU rewrite mode disabled)
Jump to a specified address in the flash memory
On-chip oscillator mode
(main clock stops) program
NOTES :
1. Set the FMR01 bit to 1 (CPU rewrite mode) before setting the FMSTP bit to 1.
2. Before switching to a different clock source for the CPU, make sure the designated clock is stable.
3. Insert a 30
µs wait time in a program. Do not access the flash memory during this wait time.
Write 1 to the FMSTP bit (flash memory stops.
low power consumption mode)
(1)
Wait until the flash memory circuit stabilizes
(30
µs)
(3)
Write 0 to the FMSTP bit
(flash memory operation)
Turn main clock on→wait until oscillation
stabilizes
→switch the clock source for CPU
clock
(2)