PIC16C72-02E/SP View Datasheet(PDF) - Microchip Technology
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PIC16C72-02E/SP Datasheet PDF : 124 Pages
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3.3 PORTC and the TRISC Register
PORTC is an 8-bit wide bi-directional port. The corre-
sponding data direction register is TRISC. Setting a
TRISC bit (=1) will make the corresponding PORTC pin
an input, i.e., put the corresponding output driver in a
hi-impedance mode. Clearing a TRISC bit (=0) will
make the corresponding PORTC pin an output, i.e., put
the contents of the output latch on the selected pin.
PORTC is multiplexed with several peripheral functions
(Table 3-5). PORTC pins have Schmitt Trigger input
buffers.
When enabling peripheral functions, care should be
taken in defining TRIS bits for each PORTC pin. Some
peripherals override the TRIS bit to make a pin an out-
put, while other peripherals override the TRIS bit to
make a pin an input. Since the TRIS bit override is in
effect while the peripheral is enabled, read-modify-
write instructions (BSF, BCF, XORWF) with TRISC as
destination should be avoided. The user should refer to
the corresponding peripheral section for the correct
TRIS bit settings.
EXAMPLE 3-1: INITIALIZING PORTC
BCF STATUS, RP0 ; Select Bank 0
CLRF PORTC
; Initialize PORTC by
; clearing output
; data latches
BSF STATUS, RP0 ; Select Bank 1
MOVLW 0xCF
; Value used to
; initialize data
; direction
MOVWF TRISC
; Set RC<3:0> as inputs
; RC<5:4> as outputs
; RC<7:6> as inputs
PIC16C72 Series
FIGURE 3-5:
PORTC BLOCK DIAGRAM
(PERIPHERAL OUTPUT
OVERRIDE)
PORT/PERIPHERAL Select(2)
Peripheral Data Out
0
Data bus D Q
WR
1
PORT
CK Q
Data Latch
WR
TRIS
DQ
CK Q
TRIS Latch
RD TRIS
Peripheral
OE(3)
Q
VDD
P
I/O
pin(1)
N
VSS
Schmitt
Trigger
D
RD
EN
PORT
Peripheral input
Note 1:
2:
3:
I/O pins have diode protection to VDD and VSS.
Port/Peripheral select signal selects between port
data and peripheral output.
Peripheral OE (output enable) is only activated if
peripheral select is active.
© 1998 Microchip Technology Inc.
Preliminary
DS39016A-page 23
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