
PIC18C601/801
DS39541A-page 124
Advance Information
2001 Microchip Technology Inc.
9.9
PORTJ, LATJ, and TRISJ
Registers
PORTJ is an 8-bit wide, bi-directional I/O port. The cor-
responding data direction register is TRISJ. Setting a
TRISJ bit (= 1) will make the corresponding PORTJ pin
an input (i.e., put the corresponding output driver in a
Hi-Impedance mode). Clearing a TRISJ bit (= 0) will
make the corresponding PORTJ pin an output (i.e., put
the contents of the output latch on the selected pin).
Read-modify-write operations on the LATJ register
read and write the latched output value for PORTJ.
PORTJ is multiplexed with de-multiplexed system data
bus D7:D0, when device is configured in 8-bit execution
mode. Register MEMCON configures PORTJ as I/O or
system bus pins.
EXAMPLE 9-10:
INITIALIZING PORTJ
FIGURE 9-19:
PORTJ BLOCK DIAGRAM
IN I/O MODE
Note:
PORTJ is available only on PIC18C801
devices.
Note:
On Power-on Reset, PORTJ defaults to
system bus signals.
CLRF
PORTJ
; Initialize PORTJ by
; clearing output
; data latches
CLRF
LATJ
; Alternate method
; to clear output
; data latches
MOVLW
0CFh
; Value used to
; initialize data
; direction
MOVWF
TRISJ
; Set RJ3:RJ0 as inputs
; RJ5:RJ4 as outputs
; RJ7:RJ6 as inputs
Data
Bus
WR LATJ
WR TRISJ
RD PORTJ
Data Latch
TRIS Latch
RD TRISJ
Schmitt
Trigger
Input
Buffer
I/O pin(1)
Q
D
CK
Q
D
CK
EN
QD
EN
RD LATJ
or
PORTJ
Note 1: I/O pins have diode protection to VDD and VSS.