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3.8.4
CPU Intermittent operation mode
The CPU intermittent operation mode causes the CPU to operate intermittently with an
operating clock supplied to the CPU or resources to reduce power consumption.
I Operation in CPU Intermittent Operation Mode CPU
The CPU intermittent operation mode halts the clock supplied to the CPU at every instruction execution
when the CPU accesses registers, internal memory, I/O, or resources delaying to start the internal
bus.Decreasing the CPU processing speed while supplying a high-speed clock to resources reduces the
power consumption.
• The count of machine cycles in which clock supply to the CPU halts is set by the CG1 and CG0 bits in
the low-power consumption mode control register (LPMCR).
• The instruction execution time in the CPU intermittent operation mode is determined by adding the
normal execution time to the compensation value obtained by multiplying count of accesses to registers,
internal memory, and resources by halt cycle count.
Figure 3.8-1 shows the clock operation in the CPU intermittent operation mode.
Figure 3.8-5 Clock Operation in CPU Intermittent Operation Mode
Peripheral clock
CPU clock
Suspended cycle
CHAPTER 3 CPU
1-instruction
execution
cycle
Internal bus starts
133
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