Intel 8XC196MD, 8XC196MH, 8XC196MC manual Bidirectional Port Pin Configurations, Sfdir

I/O PORTS

Table 6-6. Logic Table for Bidirectional Ports in I/O Mode

Configuration	Complementary Output		Open-drain	Input
			Output
Px_MODE	0	0	0	0
Px_DIR	0	0	1	1
SFDIR	X	X	X	X
SFDATA	X	X	X	X
Px_REG	0	1	0, 1 (Note 2)	1
Q1	off	on	off	off
Q2	on	off	on, off (Note 2)	off
Px_PIN	0	1	X (Note 3)	high impedance (Note 4)

NOTES:

1.X = Don’t care.

2.If Px_REG is cleared, Q2 is on; if Px_REG is set, Q2 is off.

3.Px_PIN contains the current value on the pin.

4.During reset and until the first write to Px_MODE, Q4 is on.

Table 6-7. Logic Table for Bidirectional Ports in Special-function Mode

Configuration	Complementary Output		Open-drain	Input
			Output
Px_MODE	1	1	1	1
Px_DIR	0	0	1	1
SFDIR	0	0	1	1
SFDATA	0	1	0, 1 (Note 2)	1
Px_REG	X	X	X	1
Q1	off	on	off	off
Q2	on	off	on, off (Note 2)	off
Px_PIN	0	1	X (Note 3)	high impedance (Note 4)

NOTES:

1.X = Don’t care.

2.If Px_REG is cleared, Q2 is on; if Px_REG is set, Q2 is off.

3.Px_PIN contains the current value on the pin.

4.During reset and until the first write to Px_MODE, Q4 is on.

6.3.2Bidirectional 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)

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