Datasheet

 2010-2012 Microchip Technology Inc. DS41413C-page 129
PIC12(L)F1822/PIC16(L)F1823
12.3 PORTC Registers
(PIC16(L)F1823 only)
PORTC is a 6-bit wide, bidirectional port. The
corresponding data direction register is TRISC
(Register 12-8). 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).
Example 12-2 shows how to initialize PORTC.
Reading the PORTC register (Register 12-7) reads the
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 (Register 12-8) 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
read ‘0’.
12.3.1 ANSELC REGISTER
The ANSELC register (Register 12-10) 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 affect 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
port.
EXAMPLE 12-2: INITIALIZING PORTC
12.3.2 PORTC FUNCTIONS AND OUTPUT
PRIORITIES
Each PORTC pin is multiplexed with other functions. The
pins, their combined functions and their output priorities
are briefly described here. For additional information,
refer to the appropriate section in this data sheet.
When multiple outputs are enabled, the actual pin
control goes to the peripheral with the lowest number in
the following lists.
Analog input and some digital input functions are not
included in the list below. These input functions can
remain active when the pin is configured as an output.
Certain digital input functions override other port
functions and are included in the priority list.
RC0
1. SCL (MSSP)
2. SCK (MSSP)
RC1
1. SDA (MSSP)
R
C2
1. SDO (MSSP)
2. P1D
R
C3
1. P1C
R
C4
1. MDOUT
2. SRNQ
3. C2OUT
4. TX/CK
5. P1B
RC5
1. RX/DT
2. CCP1/P1A
Note: The ANSELC register must be initialized
to configure an analog channel as a digital
input. Pins configured as analog inputs
will read ‘0’.
BANKSEL PORTC ;
CLRF PORTC ;Init PORTC
BANKSEL LATC ;Data Latch
CLRF LATC ;
BANKSEL ANSELC
CLRF ANSELC ;Make RC<5:0> digital
BANKSEL TRISB ;
MOVLW B’00110000’;Set RC<5:4> as inputs
;and RC<3:0> as outputs
MOVWF TRISC ;