PIC16F720-ESLASHML datasheet(62/244 Pages) MICROCHIP

62 / 244 page

PIC16F/LF720/721

DS41430A-page 62

 2010 Microchip Technology Inc.

6.3

PORTC and TRISC Registers

PORTC is a 8-bit wide, bidirectional port. The

corresponding

data

direction

TRISC

(Register 6-12). 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 6-3 shows how to initialize PORTC.

Reading the PORTC register (Register 6-11) 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.

The TRISC register (Register 6-12) 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’.

EXAMPLE 6-3:

INITIALIZING PORTC

6.3.1

ANSELC REGISTER

The ANSELC register (Register 6-13) 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

output 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.

BANKSEL PORTC

;

CLRF

PORTC

;Init PORTC

BANKSEL TRISC

;

MOVLW

B‘00001100’

;Set RC<3:2> as inputs

MOVWF

TRISC

;and set RC<7:4,1:0>

;as outputs

PORTC: PORTC REGISTER

R/W-x

RC7

RC6

RC5

RC4

RC3

RC2

RC1

RC0

bit 7

bit 0

Legend:

R = Readable bit

W = Writable bit

U = Unimplemented bit, read as ‘0’

-n = Value at POR

‘1’ = Bit is set

‘0’ = Bit is cleared

x = Bit is unknown

bit 7-0

RC<7:0>: PORTC General Purpose I/O Pin bits

= Port pin is > VIH

= Port pin is < VIL

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