M38197 データシートの表示（PDF） - MITSUBISHI ELECTRIC

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M38197

SINGLE-CHIP 8-BIT MICROCOMPUTER

MITSUBISHI ELECTRIC  

MITSUBISHI MICROCOMPUTERS

3819 Group

SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

NOISE FILTER

The noise filter uses a sampling clock to remove the noise compo-

nent digitally from the input signal of P45/INT1/ZCR pin. The

sampling clock can be selected from 8 µs, 16 µs, or 32 µs (at

f(XIN)= 8.38 MHz) and this is used to change the noise component

to be removed. It is also possible to generate an internal trigger

and INT1/ZCR interrupt request directly without passing through

the noise filter. When passing through the noise filter, either both-

sided edge detection or one-sided edge detection can be selected

as the interrupt request generating source. The zero cross detec-

tion control register is used for this selection. Furthermore, switch

between rising edge and falling edge is performed with the bit 1 of

the interrupt edge selection register (address 003A16).

Input signal from

P45/INT1/ZCR pin

Sampling clock

RESET

DQ

C

R

A D QB

C

R

Fig. JE-4 Noise filter circuit diagram

S QC

R

DQ

C

R

One-sided/both-sided edge

detection selection bit

(bit 4 of ZCRCON)

“0”

INT1/ZCR

“1”

interrupt request

RESET

Sampling clock

P45/INT1/ZCR

Input signal from

P45/INT1/ZCR pin

A

B

C

INT1/ZCR

(one-sided edge)

interrupt request (both-sided edge)

Fig. JE-5 Timing of noise filter circuit

0V

(Note 1)

(Note 2)

Switched with

bit 4 of ZCRCON

Notes 1 : Ignored this because of treating this as noise

2 : INT1/ZCR interrupt request occurs

44

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