Datasheet

 2000-2013 Microchip Technology Inc. DS30569C-page 37
PIC16F870/871
4.3 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 4-5). 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
the destination should be avoided. The user should
refer to the corresponding peripheral section for the
correct TRIS bit settings.
FIGURE 4-5: PORTC BLOCK DIAGRAM
(PERIPHERAL OUTPUT
OVERRIDE)
TABLE 4-5: PORTC FUNCTIONS
TABLE 4-6: SUMMARY OF REGISTERS ASSOCIATED WITH PORTC
Port/Peripheral Select
(2)
Data Bus
WR
PORT
WR
TRIS
RD
Data Latch
TRIS Latch
RD TRIS
Schmitt
Trigger
QD
Q
CK
QD
EN
Peripheral Data Out
0
1
QD
Q
CK
P
N
V
DD
Vss
PORT
Peripheral
OE
(3)
Peripheral Input
I/O
pin
(1)
Note 1: I/O pins have diode protection to VDD and VSS.
2: Port/Peripheral Select signal selects between
port data and peripheral output.
3: Peripheral OE (Output Enable) is only activated
if Peripheral Select is active.
Name Bit# Buffer Type Function
RC0/T1OSO/T1CKI bit0 ST Input/output port pin or Timer1 oscillator output/Timer1 clock input.
RC1/T1OSI bit1 ST Input/output port pin or Timer1 oscillator input.
RC2/CCP1 bit2 ST Input/output port pin or Capture1 input/Compare1 output/
PWM1 output.
RC3 bit3 ST Input/output port pin.
RC4 bit4 ST Input/output port pin.
RC5 bit5 ST Input/output port pin.
RC6/TX/CK bit6 ST Input/output port pin or USART Asynchronous Transmit or
Synchronous Clock.
RC7/RX/DT bit7 ST Input/output port pin or USART Asynchronous Receive or
Synchronous Data.
Legend: ST = Schmitt Trigger input
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Value on:
POR, BOR
Value on
all other
RESETS
07h PORTC RC7 RC6 RC5 RC4 RC3 RC2 RC1 RC0
xxxx xxxx uuuu uuuu
87h TRISC PORTC Data Direction Register
1111 1111 1111 1111
Legend: x = unknown, u = unchanged