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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:
• 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 00 0 0
P
x
_DIR 00 1 1
SFDIR XX X X
SFDATA XX 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. 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 11 1 1
P
x
_DIR 00 1 1
SFDIR 00 1 1
SFDATA 0 1 0, 1 (Note 2) 1
P
x
_REG XX 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. 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.