PIC16LF1824T39A_12 Datasheet, PDF (124/418 Pages) Microchip Technology – 20-Pin Flash Microcontrollers with XLP Technology

PIC16LF1824T39A
12.3 PORTC Registers
PORTC is a 6-bit wide, bidirectional port. The
corresponding data direction register is TRISC
(Register 12-10). 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 12-9) 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 12-10) 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’.
The INLVLC register (Register 12-14) controls the input
voltage threshold for each of the available PORTC
input pins. A selection between the Schmitt Trigger
CMOS or the TTL Compatible thresholds is available.
The input threshold is important in determining the
value of a read of the PORTC register and also the
level at which an interrupt-on-change occurs, if that
feature is enabled. See Section 31.4 “DC Character-
istics: PIC16LF1824T39A-I” for more information on
threshold levels.
Note:
Changing the input threshold selection
should be performed while all peripheral
modules are disabled. Changing the
threshold level during the time a module is
active may inadvertently generate a
transition associated with an input pin,
regardless of the actual voltage level on
that pin.
12.3.1 WEAK PULL-UPS
Each of the PORTC pins has an individually configurable
internal weak pull-up. Control bits WPUC<5:0> enable or
disable each pull-up (see Register 12-13). Each weak
pull-up is automatically turned off when the port pin is
configured as an output. All pull-ups are disabled on a
Power-on Reset by the WPUEN bit of the OPTION_REG
register.
12.3.2 ANSELC REGISTER
The ANSELC register (Register 12-12) 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
executing read-modify-write instructions on the affected
port.
Note:
The ANSELC register must be initialized
to configure an analog channel as a digital
input. Pins configured as analog inputs
will read ‘0’.
EXAMPLE 12-2: INITIALIZING PORTC
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
;
DS41657A-page 124
Preliminary
 2012 Microchip Technology Inc.