
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
MITSUBISHI MICROCOMPUTERS
3825 Group
40
Fig. 39 Internal state of microcomputer immediately after re-
set
Fig. 38 Example of reset circuit
RESET CIRCUIT
To reset the microcomputer, RESET pin should be held at an “L”
level for 2 µs or more. Then the RESET pin is returned to an “H”
level (the power source voltage should be between V
CC(min.) and
5.5 V, and the quartz-crystal oscillator should be stable), reset is
released. After the reset is completed, the program starts from the
address contained in address FFFD16 (high-order byte) and ad-
dress FFFC
16 (low-order byte). Make sure that the reset input
voltage meets V
IL spec. when a power source voltage passes
V
CC(min.).
P
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P
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R
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Power source voltage
detection circuit
V
I
L
s
p
e
c
.
0
V
0
V
V
CC
R
E
S
E
T
V
CC
RESET
ote:
e contents o
a
ot
er reg
sters an
are un
e
ne
a
ter
reset, so they must be initialized by software.
✕ : Undefined
e
g
s
t
e
r
c
o
n
t
e
n
t
s
r
e
s
s
0000
16
0002
16
0003
16
0004
16
0005
16
0006
16
0008
16
0009
16
000
16
000
16
0
0
0
1
6
0
0
0
1
6
000
16
0
0
0
1
6
0010
16
0011
16
0016
16
0017
16
0019
16
001
16
001
16
0020
16
0021
16
0022
16
0023
16
0024
16
0025
16
0026
16
0027
16
0028
16
0029
16
002
16
0034
16
0038
16
0039
16
003
16
003
16
0
0
3
1
6
0
0
3
1
6
003
16
0
0
3
1
6
H
L
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
21
22
23
24
25
2
6
2
7
2
8
2
9
3
0
3
1
3
2
3
3
3
4
1
2
3
4
5
6
7
8
9
3
5
3
6
3
7
3
8
3
9
4
0
4
1
4
2
4
3
Timer Y (low)
Port P5 direction register
Port P6
Port P6 direction register
PULL register B
Timer Y (high)
Serial I/O control register
UART control register
Timer X (high)
Timer X (low)
Timer X mode register
Timer Y mode register
Timer 123 mode register
Serial I/O status register
Port P7
Port P7 direction register
Port P8
A-D control register
Segment output enable register
LCD mode register
PULL register A
Interrupt edge selection register
CPU mode register
Interrupt request register 1
Interrupt request register 2
Interrupt control register 1
Interrupt control register 2
Processor status register
Program counter
Port P5
Port P4 direction register
Port P4
Port P3
Port P2 direction register
Port P2
Port P1 output control register
Port P1
Port P0
Port P8 direction register
Timer 1
Timer 2
Timer 3
Clock output control register
111000 00
100000 00
000010 0
0
1
0
0
1
0000
✕ 1
✕✕
✕✕ ✕✕
0
0
1
6
0
0
1
6
0
0
1
6
0
0
1
6
00
16
00
16
00
16
0
0
1
6
1
6
1
6
1
6
1
6
1
6
0
1
1
6
16
0
0
1
6
00
16
0
0
1
6
0
0
1
6
00
16
0
0
1
6
00
16
00
16
0
0
1
6
0
0
1
6
0
0
1
6
0
0
1
6
0
0
1
6
0
0
1
6
0
0
1
6
0
0
1
6
0
0
1
6
0
0
1
6
0
0
1
6
00
16
0
0
1
6
0
1
1
6
0
0
1
6
C
o
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t
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n
t
s
o
f
a
d
d
r
e
s
s
F
F
F
D
1
6
C
o
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e
n
t
s
o
f
a
d
d
r
e
s
s
F
F
F
C1
6
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