M38197 Mitsubishi, M38197 Datasheet - Page 44

• Manufacturer Part Number: M38197
• Description: SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
• Manufacturer: Mitsubishi

NOISE FILTER
The noise filter uses a sampling clock to remove the noise compo-
nent digitally from the input signal of P4
sampling clock can be selected from 8 s, 16 s, or 32 s (at
f(X
to be removed. It is also possible to generate an internal trigger
and INT
Fig. JE-4 Noise filter circuit diagram
Fig. JE-5 Timing of noise filter circuit
44
IN
)= 8.38 MHz) and this is used to change the noise component
Input signal from
P4
INT
interrupt request
1
/ZCR interrupt request directly without passing through
Sampling clock
5
1
/INT
/ZCR
1
/ZCR pin
RESET
Input signal from
P4
(both-sided edge)
(one-sided edge)
Sampling clock
5
P4
/INT
5
/INT
1
D
/ZCR pin
C
RESET
R
1
/ZCR
Q
C
A
B
A
5
D
/INT
C
R
Q
1
/ZCR pin. The
B
(Note 2)
S
R
Q
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 003A
(Note 1)
C
D
C
Notes 1
R
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
Q
2
: Ignored this because of treating this as noise
: INT
MITSUBISHI MICROCOMPUTERS
1
/ZCR interrupt request occurs
One-sided/both-sided edge
detection selection bit
(bit 4 of ZCRCON)
“0”
“1”
3819 Group
Switched with
bit 4 of ZCRCON
0 V
INT
interrupt request
1
/ZCR
16
).