PIC18F47J53 Datasheet, PDF (152/586 Pages) Microchip Technology – 28/44-Pin, High-Performance USB Microcontrollers with nanoWatt XLP Technology

PIC18F47J53 FAMILY
10.4 PORTC, TRISC and LATC
Registers
PORTC is an 8-bit wide, bidirectional 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 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
(see Table ). The 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 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.
Pins RC4 and RC5 are multiplexed with the USB module.
Depending on the configuration of the module, they can
serve as the differential data lines for the on-chip USB
transceiver, or the data inputs from an external USB
transceiver. When used as general purpose inputs, both
RC4 and RC5 input buffers depend on the level of the
voltage applied to the VUSB pin, instead of VDD like all
other general purpose I/O pins. Therefore, if the RC4 or
RC5 general purpose input capability will be used, the
VUSB pin should not be left floating.
Unlike other PORTC pins, RC4 and RC5 do not have
TRISC bits associated with them. As digital ports, they
can only function as digital inputs. When configured for
USB operation, the data direction is determined by the
configuration and status of the USB module at a given
time. If an external transceiver is used, RC4 and RC5
always function as inputs from the transceiver. If the on-
chip transceiver is used, the data direction is determined
by the operation being performed by the module at that
time.
Note:
On a Power-on Reset, PORTC pins
(except RC2, RC4 and RC5) are config-
ured as digital inputs. RC2 will default as
an analog input (controlled by the
ANCON1 register). To use pins RC4 and
RC5 as digital inputs, the USB module
must be disabled (UCON<3> = 0) and the
on-chip USB transceiver must be disabled
(UCFG<3> = 1). The internal USB
transceiver has a POR value of enabled.
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 10-4: INITIALIZING PORTC
CLRF PORTC ; Initialize PORTC by
; clearing output
; data latches
CLRF LATC
; Alternate method
; to clear output
; data latches
MOVLW 0x3F
; Value used to
; initialize data
; direction
MOVWF TRISC ; Set RC<5:0> as inputs
; RC<7:6> as outputs
MOVLB 0x0F
; ANCON register is not in
Access Bank
BSF ANCON1,PCFG11
;Configure RC2/AN11 as
digital input
DS39964B-page 152
Preliminary
 2010 Microchip Technology Inc.