Bidirectional Port Pin Configurations - Intel 8XC196MC User Manual

Table 6-6. Logic Table for Bidirectional Ports in I/O Mode
Configuration
P x _MODE
P x _DIR
SFDIR
SFDATA
P x _REG
Q1
Q2
P x _PIN
NOTES:
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.
During reset and until the first write to P x _MODE, Q4 is on.
4.
Table 6-7. Logic Table for Bidirectional Ports in Special-function Mode
Configuration
P x _MODE
P x _DIR
SFDIR
SFDATA
P x _REG
Q1
Q2
P x _PIN
NOTES:
1. X = Don't care.
2. If P x _REG is cleared, Q2 is on; if P x _REG is set, Q2 is off.
P x _PIN contains the current value on the pin.
3.
4. During reset and until the first write to P x _MODE, Q4 is on.
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:
•
complementary output (output only)
•
high-impedance input or open-drain output (input, output, or bidirectional)
Complementary Output
0 0
0 0
X X
X X
0 1
off on
on off
0 1
Complementary Output
1 1
0 0
0 0
0 1
X X
off on
on off
0 1
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Open-drain
Output
0
1
X
X
0, 1 (Note 2)
off
on, off (Note 2)
X (Note 3) high impedance (Note 4)
Open-drain
Output
1
1
1
0, 1 (Note 2)
X
off
on, off (Note 2)
X (Note 3) high impedance (Note 4)
I/O PORTS
Input
0
1
X
X
1
off
off
Input
1
1
1
1
1
off
off
6-9