Datasheet

PIC16C7X
DS30390E-page 48  1997 Microchip Technology Inc.
5.3 PORTC and TRISC Registers
PORTC is an 8-bit bi-directional port. Each pin is indi-
vidually configurable as an input or output through the
TRISC register. PORTC is multiplexed with several
peripheral functions (Table 5-5). 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 5-3: INITIALIZING PORTC
BCF STATUS, RP0 ; Select Bank 0
BCF STATUS, RP1 ; PIC16C76/77 only
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
Applicable Devices
72
73 73A 74 74A 76 77
FIGURE 5-6: PORTC BLOCK DIAGRAM
(PERIPHERAL OUTPUT
OVERRIDE)
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
VDD
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.
TABLE 5-5: PORTC FUNCTIONS
Name Bit# Buffer Type Function
RC0/T1OSO/T1CKI
bit0
ST Input/output port pin or Timer1 oscillator output/Timer1 clock input
RC1/T1OSI/CCP2
(1)
bit1 ST Input/output port pin or Timer1 oscillator input or Capture2 input/
Compare2 output/PWM2 output
RC2/CCP1 bit2 ST Input/output port pin or Capture1 input/Compare1 output/PWM1
output
RC3/SCK/SCL bit3 ST
RC3 can also be the synchronous serial clock for both SPI and I
2
C
modes.
RC4/SDI/SDA bit4 ST
RC4 can also be the SPI Data In (SPI mode) or data I/O (I
2
C mode).
RC5/SDO bit5 ST Input/output port pin or Synchronous Serial Port data output
RC6/TX/CK
(2)
bit6 ST Input/output port pin or USART Asynchronous Transmit, or USART
Synchronous Clock
RC7/RX/DT
(2)
bit7 ST Input/output port pin or USART Asynchronous Receive, or USART
Synchronous Data
Legend: ST = Schmitt Trigger input
Note 1: The CCP2 multiplexed function is not enabled on the PIC16C72.
2: The TX/CK and RX/DT multiplexed functions are not enabled on the PIC16C72.