Intel 8XC196NP User Manual page 421

8XC196NP, 80C196NU USER'S MANUAL
Px_DIR
P x _DIR
x = 1–4
Each pin of port x can operate in any of the standard I/O modes of operation: complementary output,
open-drain output, or high-impedance input. The port x I/O direction (P x _DIR) register determines the
I/O direction for each port x pin. The register settings for an open-drain output or a high-impedance
input are identical. An open-drain output configuration requires an external pull-up. A high-impedance
input configuration requires that the corresponding bit in P x _REG be set.
7
x = 1–3
7
x = 4
Bit Bit
Number Mnemonic
7:0 PIN7:0
Table C-10. P x _DIR Addresses and Reset Values
C-30
PIN7 PIN6 PIN5
— — —
Port x Pin y Direction
This bit selects the P x . y direction:
0 = complementary output (output only)
1 = input or open-drain output (input, output, or bidirectional Open-
drain outputs require external pull-ups.
Register
P1_DIR
P2_DIR
P3_DIR
P4_DIR
PIN4 PIN3
— PIN3
Function
Address Reset Value
1FD2H FFH
1FD3H FFH
1FDAH FFH
1FDBH FFH
Address: Table C-10
Reset State:
0
PIN2 PIN1 PIN0
0
PIN2 PIN1 PIN0