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INPUT/OUTPUT PORTS
Register Name:
Register Mnemonic:
Register Function:
15
Bit
Mnemonic
PC7:0
Port Control
7:0
NOTE: Reserved register bits are shown with gray shading. Reserved bits must be written
to a logic zero to ensure compatibility with future Intel products.
13.2.2 Port Direction Register
The Port Direction Register (Figure 13-5) controls the direction (input or output) for each pin pro-
grammed as a general-purpose I/O port. The Port Direction bit has no effect on output-only port
pins. These unused direction control bits can be used for bit storage.
The Port Direction Register is read/write. When read, the register returns the value written to it
previously. Pins with their direction fixed return the value in this register, not a value indicating
their true direction. The direction of a port pin assigned to a peripheral function is controlled by
the peripheral; the Port Direction value is ignored.
13-8
Port Control Register
PxCON (P1CON, P2CON, P3CON)
Selects port or peripheral function for a port pin.
Reset
Bit Name
State
FFH
Figure 13-4. Port Control Register (PxCON)
P
P
P
P
C
C
C
C
7
6
5
4
Function
When the PC bit for a specific pin is set, the
associated integrated peripheral controls both
pin direction and pin data. Clearing the PC bit
makes the pin a general-purpose I/O port.
NOTE: PC7 and PC6 do not exist for Port 3.
0
P
P
P
P
C
C
C
C
3
2
1
0
A1312-0A
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