Datasheet

© 2006 Microchip Technology Inc. DS39564C-page 93
PIC18FXX2
9.3 PORTC, TRISC and LATC
Registers
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).
The Data Latch register (LATC) is also memory
mapped. Read-modify-write operations on the LATC
register reads and writes the latched output value for
PORTC.
PORTC is multiplexed with several peripheral functions
(Table 9-5). 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. The user should refer to the corre-
sponding peripheral section for the correct TRIS bit
settings.
The pin override value is not loaded into the TRIS reg-
ister. This allows read-modify-write of the TRIS register,
without concern due to peripheral overrides.
RC1 is normally configured by configuration bit,
CCP2MX, as the default peripheral pin of the CCP2
module (default/erased state, CCP2MX = ’1’).
EXAMPLE 9-3: INITIALIZING PORTC
FIGURE 9-7: PORTC BLOCK DIAGRAM (PERIPHERAL OUTPUT OVERRIDE)
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 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
Data Bus
WR LATC or
WR TRISC
RD TRISC
QD
Q
CK
Q
D
EN
Peripheral Data Out
0
1
QD
Q
CK
RD PORTC
Peripheral Data In
WR PORTC
RD LATC
Peripheral Output
Schmitt
Port/Peripheral Select
(2)
Enable
(3)
P
N
VSS
VDD
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 (input) and peripheral output.
3: Peripheral Output Enable is only active if peripheral select is active.
Data Latch
TRIS Latch
Trigger