
PIC18F2X1X/4X1X
DS39636D-page 106
2009 Microchip Technology Inc.
9.4
PORTD, TRISD and LATD
Registers
PORTD is an 8-bit wide, bidirectional port. The corre-
sponding data direction register is TRISD. Setting a
TRISD bit (= 1) will make the corresponding PORTD
pin an input (i.e., put the corresponding output driver in
a high-impedance mode). Clearing a TRISD bit (= 0)
will make the corresponding PORTD pin an output (i.e.,
put the contents of the output latch on the selected pin).
The Data Latch register (LATD) is also memory
mapped. Read-modify-write operations on the LATD
register read and write the latched output value for
PORTD.
All pins on PORTD are implemented with Schmitt
Trigger input buffers. Each pin is individually
configurable as an input or output.
Three of the PORTD pins are multiplexed with outputs
P1B, P1C and P1D of the enhanced CCP module. The
operation of these additional PWM output pins is
PORTD can also be configured as an 8-bit wide micro-
processor port (Parallel Slave Port) by setting control
bit, PSPMODE (TRISE<4>). In this mode, the input
Port” for additional information on the Parallel Slave
Port (PSP).
EXAMPLE 9-4:
INITIALIZING PORTD
Note:
PORTD is only available on 40/44-pin
devices.
Note:
On a Power-on Reset, these pins are
configured as digital inputs.
Note:
When the enhanced PWM mode is used
with either dual or quad outputs, the PSP
functions of PORTD are automatically
disabled.
CLRF
PORTD
; Initialize PORTD by
; clearing output
; data latches
CLRF
LATD
; Alternate method
; to clear output
; data latches
MOVLW
0CFh
; Value used to
; initialize data
; direction
MOVWF
TRISD
; Set RD<3:0> as inputs
; RD<5:4> as outputs
; RD<7:6> as inputs