PORTC is an 8-bit wide, bidirectional port. The
corresponding data direction register is TRISC
11-8). 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., enable the
output driver and put the contents of the output latch
on the selected pin).
initialize an I/O port.
Reading the PORTC register
status of the pins, whereas writing to it will write to the
PORT latch. All write operations are read-modify-write
operations. Therefore, a write to a port implies that the
port pins are read, this value is modified and then written
to the PORT data latch (LATC).
The TRISC register
11-8) controls the PORTC
pin output drivers, even when they are being used as
analog inputs. The user should ensure the bits in the
TRISC register are maintained set when using them as
analog inputs. I/O pins configured as analog input always
The ANSELC register
11-10) is used to
configure the Input mode of an I/O pin to analog.
Setting the appropriate ANSELC bit high will cause all
digital reads on the pin to be read as ‘0’ and allow
analog functions on the pin to operate correctly.
The state of the ANSELC bits has no effect on digital out-
put functions. A pin with TRIS clear and ANSELC set will
still operate as a digital output, but the Input mode will be
analog. This can cause unexpected behavior when exe-
cuting read-modify-write instructions on the affected
The ANSELC bits default to the Analog
mode after Reset. To use any pins as
digital general purpose or peripheral
inputs, the corresponding ANSEL bits
must be initialized to ‘0’ by user software.
2011 Microchip Technology Inc.
PORTC FUNCTIONS AND OUTPUT
Each PORTC pin is multiplexed with other functions. The
pins, their combined functions and their output priorities
are shown in
When multiple outputs are enabled, the actual pin
control goes to the peripheral with the highest priority.
Analog input and some digital input functions are not
included in the output priority list. These input functions
shows how to
can remain active when the pin is configured as an
output. Certain digital input functions override other
11-7) reads the
port functions and are included in the output priority list.
Priority listed from highest to lowest.
Default pin (see APFCON register).
Alternate pin (see APFCON register).
PORTC OUTPUT PRIORITY