User`s manual

121
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER
and ON-SCREEN DISPLAY CONTROLLER
MITSUBISHI MICROCOMPUTERS
Rev. 1.0
M37281MAH–XXXSP,M37281MFH–XXXSP
M37281MKH–XXXSP,M37281EKSP
Fig.8.14.4 State Transitions of System Clock
Reset
The example assumes that 8 MHz is being applied to the X IN pin and 32 kHz to the X CIN pin. The φ indicates the internal clock.
WIT instruction
CM7 : Internal system clock selection bit
0 : X
IN -X OUT selected (high-speed mode)
1 : X
CIN -X COUT selected (low-speed mode)
CPU mode register
(Address : 00FB
16 )
CM6 : Main clock (X IN –X OUT ) stop bit
0 : Oscillating
1 : Stopped
8 MHz oscillating
32 kHz oscillating
φ is stopped (HIGH)
Timer operating
8 MHz oscillating
32 kHz oscillating
f(φ) = 4 MHz
8 MHz stopped
32 kHz stopped
φ is stopped (HIGH)
8 MHz oscillating
32 kHz oscillating
φ is stopped (HIGH)
Timer operating
(Note 3)
8 MHz oscillating
32 kHz oscillating
f(φ) = 16 kHz
8 MHz stopped
32 kHz stopped
φ is stopped (HIGH)
8 MHz stopped
32 kHz stopped
φ = stopped (HIGH )
8 MHz stopped
32 kHz oscillating
f(φ) = 16 kHz
8 MHz stopped
32 kHz oscillating
φ is stopped (HIGH)
Timer operating
(Note 3)
Interrupt
STP instruction
Interrupt (Note 1)
WIT instruction
Interrupt
WIT instruction
Interrupt
STP instruction
Interrupt (Note 2)
STP instruction
Interrupt (Note 2)
CM7 = 1
CM7 = 0
CM6 = 1
CM6 = 0
External INT,
timer interrupt,
or SI/O interrupt
External INT
Notes 1: When the STP state is ended, a delay of approximately 4 ms is automatically generated by timer 3 and timer 4.
2: The delay after the STP state ends is approximately 1 s.
3: When the internal clock φ divided by 8 is used as the timer count source, the frequency of the count source is 2 kHz.
The program must
allow time for 8 MHz
oscillation to stabilize
High-speed operation start
mode