Datasheet

© 2009 Microchip Technology Inc. DS39689F-page 117
PIC18F2221/2321/4221/4321 FAMILY
11.3 PORTC, TRISC and LATC
Registers
PORTC is an 8-bit wide, bidirectional port. The
corresponding Data Direction register is TRISC. Set-
ting a TRISC bit (= 1) will make the corresponding
PORTC pin an input (i.e., put the corresponding output
driver in a High-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).
The Data Latch register (LATC) is also memory
mapped. Read-modify-write operations on the LATC
register read and write the latched output value for
PORTC.
PORTC is multiplexed with several peripheral functions
(Table 11-5). The pins have Schmitt Trigger input
buffers. RC1 is normally configured by Configuration
bit, CCP2MX, as the default peripheral pin of the CCP2
module (default/erased state, CCP2MX = 1).
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. The user should refer to the corresponding
peripheral section for additional information.
The contents of the TRISC register are affected by
peripheral overrides. Reading TRISC always returns
the current contents, even though a peripheral device
may be overriding one or more of the pins.
EXAMPLE 11-3: INITIALIZING PORTC
Note: On a Power-on Reset, these pins are
configured as digital inputs.
CLRF PORTC ; Initialize PORTC by
; clearing output
; data latches
CLRF LATC ; Alternate method
; to clear output
; data latches
MOVLW 0CFh ; Value used to
; initialize data
; direction
MOVWF TRISC ; Set RC<3:0> as inputs
; RC<5:4> as outputs
; RC<7:6> as inputs