
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
MITSUBISHI MICROCOMPUTERS
38C1 Group
41
Fig. 43 State transitions of system clock
Reset release
XIN stop
XCIN stop
φ=f(ROSC)/8
CM7=0
CM6=1 (Note 5)
CM5=1
CM4=0
CM3=1
XIN stop
XCIN oscillation
φ=f(ROSC)/8
CM7=0
CM6=1 (Note 5)
CM5=1
CM4=1
CM3=1
XIN oscillation
XCIN stop
φ=f(ROSC)/8
CM7=0
CM6=1 (Note 5)
CM5=0
CM4=0
CM3=1
XIN oscillation
XCIN oscillation
φ=f(ROSC)/8
CM7=0
CM6=1(Note 5)
CM5=0
CM4=1
CM3=1
CM4
CM5
XIN stop
XCIN oscillation
φ=16kHz
CM7=1
CM6=1
CM5=1
CM4=1
CM3=* (Note 9)
XIN oscillation
XCIN oscillation
φ=16kHz
CM7=1
CM6=0 (Note 5)
CM5=0
CM4=1
CM3= * (Note 9)
CM6
CM5
XIN oscillation
XCIN stop
φ=1MHz
CM7=0
CM6=1
CM5=0
CM4=0
CM3=0
XIN oscillation
XCIN oscillation
φ=1MHz
CM7=0
CM6=1
CM5=0
CM4=1
CM3=0
CM4
XIN oscillation
XCIN stop
φ=4MHz
CM7=0
CM6=0 (Note 5)
CM5=0
CM4=0
CM3=0
XIN oscillation
XCIN oscillation
φ=4MHz
CM7=0
CM6=0 (Note 5)
CM5=0
CM4=1
CM3=0
CM4
CM7
XIN oscillation
XCIN oscillation
φ=16kHz
CM7=1
CM6=1
CM5=0
CM4=1
CM3= * (Note 9)
Ring oscillator mode
Low-speed mode
Middle-speed mode
High-speed mode
CM3
b7
b3
CM3
CM6
CM7
Notes 1: Switch the mode by the arrows shown between the mode blocks.
The all modes can be switched to the stop mode or the wait mode.
2: Timer and LCD operate in the wait mode. System is returned to the source mode
when the wait mode is ended.
3: CM4, CM5 and CM6 are retained in the stop mode. System is returned to
the ring oscillator mode (CM3=1, CM7=0).
4: When the stop mode is ended, set the oscillation stabilizing wait time in the ring oscillator mode.
5: When the stop mode is ended, set the initial value to CM6 (CM6=1).
6: Execute the transition after the oscillation used in the destination mode is stabilized.
7: When system goes to ring oscillator mode, the oscillation stabilizing wait time is not needed.
8: Do not go to the high-speed mode from the ring oscillator mode.
9: Write the proper values for destination mode beforehand.
10: The example assumes that 8 MHz is being applied to the XIN pin and 32 kHz to the XCIN pin.
f(ROSC) indicates the oscillation frequency of ring oscillator.
Main clock selection bit
0: XIN input signal
1: Ring oscillator
Port Xc switch bit
0: I/O port function (Oscillation stop)
1: XCIN, XCOUT function
XIN–XOUT oscillation stop bit
0: Oscillating
1: Stopped
Main clock division ratio selection bit
0: f(XIN)/2 (high-speed mode)
1: f(XIN)/8 (middle-speed mode)
Internal system clock selection bit
0: Main clock selected
(middle-/high-speed and ring oscillator mode)
1: XCIN–XCOUT selected
(low-speed mode)
CPU mode register
(CPUM : address 003B16, initial value: 6816)