r5f21346mnfp Renesas Electronics Corporation., r5f21346mnfp Datasheet - Page 704

• Manufacturer Part Number: r5f21346mnfp
• Description: Single-chip Mcus Incorporates The R8c Cpu Core
• Manufacturer: Renesas Electronics Corporation.

R8C/34M Group
R01UH0131EJ0100 Rev.1.00
Jun 21, 2011
Figure 33.3
33.2.10 Stopping Flash Memory
Notes:
FMR01, FMSTP: Bits in FMR0 register
2. Before switching the CPU clock source, make sure the designated
3. Insert a 60-µs wait time by a program.
1. After setting the FMR01 bit to 1 (CPU rewrite mode enabled),
In low-speed on-chip oscillator mode and low-speed clock mode, power consumption can be further reduced by
stopping the flash memory using the FMSTP bit in the FMR0 register.
Access to the flash memory is disabled by setting the FMSTP bit to 1 (flash memory stops). The FMSTP bit
must be written to by a program transferred to RAM.
When the MCU enters stop mode or wait mode while CPU rewrite mode is disabled, the power for the flash
memory is automatically turned off. It is turned back on again after the MCU exits stop mode or wait mode.
This eliminates the need to set the FMR0 register.
Figure 33.3 shows the Handling Procedure Example for Reducing Power Consumption Using FMSTP Bit.
clock is stable.
Do not access the flash memory during this wait time.
set the FMSTP bit to 1 (flash memory stops).
Transfer the FMSTP bit setting program to
the RAM
Jump to the FMSTP bit setting program
(The subsequent processing is executed
by the program in the RAM)
Handling Procedure Example for Reducing Power Consumption Using FMSTP Bit
FMSTP bit setting program
Jump to the specified address in the flash memory
Write 1 to the FMSTP bit (flash memory stops.
low power consumption state)
After writing 0 to the FMR01 bit,
write 1 (CPU rewrite mode enabled)
Enter low-speed clock mode or
low-speed on-chip oscillator mode
Stop the high-speed on-chip oscillator
Write 0 to the FMSTP bit
(flash memory operates)
Write 0 to the FMR01 bit
(CPU rewrite mode disabled)
Wait until the flash memory circuit stabilizes
(60 µ s)
Switch the clock source for the CPU clock
Process in low-speed clock mode or
low-speed on-chip oscillator mode
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33. Reducing Power Consumption
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