Renesas PCA7400 Bedienungsanleitung PDF herunterladen (Seite 84)

MITSUBISHI MICROCOMPUTERS

M37271MF-XXXSP

M37271EF-XXXSP, M37271EFSP

SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER

and ON-SCREEN DISPLAY CONTROLLER

Fig. 96. 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-XOUT selected (high-speed mode)

1 : X

CIN-XCOUT selected (low-speed mode)

CPU mode register

(Address : 00FB

16)

CM6 : Main clock (XIN–XOUT) stop bit

0 : Oscillating

1 : Stopped

8MHz oscillating

32kHz oscillating

φ is stopped (“H”)

Timer operating

8MHz oscillating

32kHz oscillating

f(φ ) = 4MHz

8MHz stopped

32kHz stopped

φ is stopped (“H”)

8MHz oscillating

32kHz oscillating

φ is stopped (“H”)

Timer operating

(Note 3)

8MHz oscillating

32kHz oscillating

f(φ ) = 16kHz

8MHz stopped

32kHz stopped

φ is stopped (“H”)

8MHz stopped

32kHz stopped

φ = stopped (“H”)

8MHz stopped

32kHz oscillating

f(φ ) = 16kHz

8MHz stopped

32kHz oscillating

φ is stopped (“H”)

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

7 = 0

6 = 1

6 = 0

External INT,

timer interrupt,

or SI/O interrupt

External INT

Notes 1: When the STP state is ended, a delay of approximately 8ms is automatically generated by timer 3 and timer 4.

2: The delay after the STP state ends is approximately 2s.

3: When the internal clock φ divided by 8 is used as the timer count source, the frequency of the count source is 2kHz.

The program must

allow time for 8MHz

oscillation to stabilize

High-speed operation

start mode

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