PIC16F7X
FIGURE 4-5:
PORTC BLOCK DIAGRAM
(PERIPHERAL OUTPUT
OVERRIDE)
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).
Port/Peripheral Select(2)
Peripheral Data Out
Data Bus
VDD
P
0
1
D
Q
WR Port
Q
CK
PORTC is multiplexed with several peripheral functions
(Table 4-5). PORTC pins have Schmitt Trigger input
buffers.
Data Latch
I/O
pin(1)
D
Q
Q
WR TRIS
RD TRIS
CK
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
output, 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, and to Section 13.1 for
additional information on read-modify-write operations.
N
TRIS Latch
VSS
Schmitt
Trigger
Peripheral
OE(3)
Q
D
EN
RD Port
Peripheral Input
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.
TABLE 4-5:
Name
PORTC FUNCTIONS
Bit# Buffer Type
Function
RC0/T1OSO/T1CKI
RC1/T1OSI/CCP2
bit0
bit1
ST
ST
Input/output port pin or Timer1 oscillator output/Timer1 clock input.
Input/output port pin or Timer1 oscillator input or Capture2
input/Compare2 output/PWM2 output.
RC2/CCP1
bit2
bit3
ST
ST
Input/output port pin or Capture1 input/Compare1 output/PWM1 output.
RC3 can also be the synchronous serial clock for both SPI and I2C
RC3/SCK/SCL
modes.
RC4/SDI/SDA
RC5/SDO
bit4
bit5
bit6
ST
ST
ST
RC4 can also be the SPI Data In (SPI mode) or Data I/O (I2C mode).
Input/output port pin or Synchronous Serial Port data output.
RC6/TX/CK
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
TABLE 4-6:
SUMMARY OF REGISTERS ASSOCIATED WITH PORTC
Value on:
POR,
BOR
Value on
all other
RESETS
Address Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
07h
87h
PORTC RC7
RC6
RC5
RC4
RC3
RC2
RC1
RC0 xxxx xxxx uuuu uuuu
TRISC PORTC Data Direction Register
1111 1111 1111 1111
Legend: x= unknown, u= unchanged
2002 Microchip Technology Inc.
DS30325B-page 35
MICROCHIP [ MICROCHIP ]
