PIC12F1822-ISLASHMF datasheet(124/398 Pages) MICROCHIP

124 / 398 page

PIC12F/LF1822/16F/LF1823

DS41413A-page 124

Preliminary

 2010 Microchip Technology Inc.

12.3

PORTC Registers

(PIC16F/LF1823 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

SCL (MSSP)

SCK (MSSP)

RC1

SDA (MSSP)

RC2

SDO (MSSP)

P1D

RC3

P1C

RC4

MDOUT

SRNQ

C2OUT

TX/CK

P1B

RC5

RX/DT

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

;

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