Intel 8XC196MD User Manual
6-9
I/O PORTS
6.3.2
Bidirectional Port Pin Configurations
Each bidirectional port pin can be individually configured to operate either as an I/O pin or as a
pin for a special-function signal. In the special-function configuration, the signal is controlled by
an on-chip peripheral or an off-chip component. In either configuration, two modes are possible:
pin for a special-function signal. In the special-function configuration, the signal is controlled by
an on-chip peripheral or an off-chip component. In either configuration, two modes are possible:
•
complementary output (output only)
•
high-impedance input or open-drain output (input, output, or bidirectional)
Table 6-6. Logic Table for Bidirectional Ports in I/O Mode
Configuration
Complementary Output
Open-drain
Output
Input
P
x
_MODE
0
0
0
0
P
x
_DIR
0
0
1
1
SFDIR
X
X
X
X
SFDATA
X
X
X
X
P
x
_REG
0
1
0, 1 (Note 2)
1
Q1
off
on
off
off
Q2
on
off
on, off (Note 2)
off
P
x
_PIN
0
1
X (Note 3)
high impedance (Note 4)
NOTES:
1.
1.
X = Don’t care.
2.
If P
x
_REG is cleared, Q2 is on; if P
x
_REG is set, Q2 is off.
3.
P
x
_PIN contains the current value on the pin.
4.
During reset and until the first write to P
x
_MODE, Q4 is on.
Table 6-7. Logic Table for Bidirectional Ports in Special-function Mode
Configuration
Complementary Output
Open-drain
Output
Input
P
x
_MODE
1
1
1
1
P
x
_DIR
0
0
1
1
SFDIR
0
0
1
1
SFDATA
0
1
0, 1 (Note 2)
1
P
x
_REG
X
X
X
1
Q1
off
on
off
off
Q2
on
off
on, off (Note 2)
off
P
x
_PIN
0
1
X (Note 3)
high impedance (Note 4)
NOTES:
1.
1.
X = Don’t care.
2.
If P
x
_REG is cleared, Q2 is on; if P
x
_REG is set, Q2 is off.
3.
P
x
_PIN contains the current value on the pin.
4.
During reset and until the first write to P
x
_MODE, Q4 is on.