Renesas PCA7401 Informacje Techniczne Pobierz pdf (Strona 84)

MITSUBISHI MICROCOMPUTERS

M37270MF-XXXSP

M37270EF-XXXSP, M37270EFSP

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

and ON-SCREEN DISPLAY CONTROLLER

Fig. 94. State transitions of system clock

Reset

The example assumes that 8 MHz is being applied to the X

pin and 32 kHz to the X

CIN

pin. The φ indicates the internal clock.

WIT instruction

: Internal system clock selection bit

0 : X

-X

OUT

selected (high-speed mode)

1 : X

CIN

-X

COUT

selected (low-speed mode)

CPU mode register

(Address : 00FB

)

: Main clock (X

–X

OUT

) 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

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

is stopped (“H”)

8MHz stopped

32kHz stopped

= 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)

= 1

= 0

= 1

= 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

1 2 ... 79 80 81 82 83 84 85 86 87 88 89 ... 96 97

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Renesas PCA7401 Informacje Techniczne Strona 84

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