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Chapter 2 CPU Basics
Standby Functions
2-4 Standby Function
2-4-1 Overview
This LSI has two sets of system clock oscillator (high speed oscillation, low speed oscillation) for two
CPU operating modes (NORMAL and SLOW), each with two standby modes (HALT and STOP). Power
consumption can be decreased with using those modes.
IDLE
OSC: Halt
XI: Oscillation
OSC: Oscillation
XI: Oscillation
NORMAL
SLOW
Program 4
Program 5
Interrupt
Interrupt
Program 5
Interrupt
Program 4
Interrupt
OSC: Oscillation
Program 2
Program1
Reset
STOP0
OSC: Halt
XI : Halt
STOP mode
NORMAL mode
SLOW mode
Program 3
HALT mode
HALT 0
OSC: Oscillation
Xl: Oscillation
CPU operation mode
STANDBY mode
STOP1
OSC: Halt
XI: Halt
HALT 1
OSC: Halt
XI: Oscillation
:CPU halt : Wait period for oscillation stabilization is inserted OSC: High-frequency oscillation clock
XI: Low-frequency oscillation clock (32 kHz)
XI: Oscillation
Figure 2-4-1 Transition Between Operation Modes