APPLICATION
2.1 I/O pins
3820 GROUP USER’S MANUAL
2–14
(5) Termination of unused pins
Table 2.1.4 shows termination of unused pins.
Terminations
Pins
Table 2.1.4 Termination of unused pins
P2
0
–P2
7
P4
1
/
φ
P4
4
/RxD
P4
5
/TxD
P4
6
/S
CLK1
P4
7
/S
RDY1
P5
0
/S
IN2
P5
1
/S
OUT2
P5
2
/S
CLK2
P5
3
/S
RDY2
P5
4
/CNTR
0
P5
5
/CNTR
1
P5
6
/T
OUT
P6
1
/RTP
1
P7
0
/X
COUT
P7
1
/X
CIN
P0
0
/SEG
24
–P0
7
/SEG
31
P1
0
/SEG
32
–P1
7
/SEG
39
P4
0
P4
2
/INT
0
P4
3
/INT
1
P5
7
/INT
2
P6
0
/INT
3
/RTP
0
V
L1
–V
L3
COM
0
–COM
3
SEG
0
–SEG
15
P3
0
/SEG
16
–P3
7
/SEG
23
After set for the input mode and put the built-in pull-down resistor in the ON
state, open.
8
1
Set for the output mode and open at “L” or “H.”
8
2
Connect each pin to V
CC
or V
SS
through each resistor of 1 k
to 10 k
.
After set for the input mode and put the built-in pull-up resistor in the ON state,
open.
8
1
Set for the output mode and open at “L” or “H.”
8
2
After disabling INT interrupts, set for the input mode, and put the built-in pull-up
resistor in the ON state, open.
8
1
Set for the output mode and open at “L” or “H.”
8
2
Connect to V
SS
level
8
1 After reset and before the built-in pull-up (pull-down) resistor is put in the ON state by software,
the built-in pull-up (pull-down) resistor is in the OFF state. Because of this, the potential at these
pins are “undefined” and the power source current may increase. Since the direction register setup
may be changed for the output mode because of a program runaway or noise, set direction
register for the input mode periodically. And make the length of wiring which is connected I/O ports
within 2 cm.
8
2 After reset and before I/O ports are switched for the output mode by software, I/O ports are set
for the input mode. Because of this, the potential at these pins are “undefined” and the power
source current may increase in the input mode. Since the direction register setup may be changed
for the input mode because of a program runaway or noise, set direction register for the output
mode periodically. And make the length of wiring which is connected I/O ports within 2 cm.
Open
Put the built-in pull-down resistor in the ON state, open.
8
1