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8XC196NP, 80C196NU USER’S MANUAL
C-30
Px_DIR
P
x
_DIR
x
= 1–4
Address:
Reset State:
Table C-10
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 0
x
= 1–3 PIN7 PIN6 PIN5 PIN4 PIN3 PIN2 PIN1 PIN0
7 0
x
= 4 ————PIN3 PIN2 PIN1 PIN0
Bit
Number
Bit
Mnemonic
Function
7:0 PIN7:0 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.
Table C-10. P
x
_DIR Addresses and Reset Values
Register Address Reset Value
P1_DIR 1FD2H FFH
P2_DIR 1FD3H FFH
P3_DIR 1FDAH FFH
P4_DIR 1FDBH FFH