PIC16LC773 datasheet(32/200 Pages) MICROCHIP

32 / 200 page

PIC16C77X

DS30275A-page 32

Advance Information

3.3

PORTC and the TRISC Register

PORTC is an 8-bit wide bi-directional port. The corre-

sponding data direction register is TRISC. Setting a

TRISC bit (=1) will make the corresponding PORTC pin

an input, i.e., put the corresponding output driver in a

hi-impedance mode. Clearing a TRISC bit (=0) will

make the corresponding PORTC pin an output, i.e., put

the contents of the output latch on the selected pin.

PORTC is multiplexed with several peripheral functions

(Table 3-5). PORTC pins have Schmitt Trigger input

buffers.

When enabling peripheral functions, care should be

taken in defining TRIS bits for each PORTC pin. Some

peripherals override the TRIS bit to make a pin an out-

put, while other peripherals override the TRIS bit to

make a pin an input. Since the TRIS bit override is in

effect while the peripheral is enabled, read-mod-

ify-write instructions (BSF, BCF, XORWF) with TRISC

as destination should be avoided. The user should refer

to the corresponding peripheral section for the correct

TRIS bit settings.

EXAMPLE 3-1:

INITIALIZING PORTC

BCF

STATUS, RP0

; Select Bank 0

CLRF

PORTC

; Initialize PORTC by

; clearing output

; data latches

BSF

STATUS, RP0

; Select Bank 1

MOVLW

0xCF

; Value used to

; initialize data

; direction

MOVWF

TRISC

; Set RC<3:0> as inputs

; RC<5:4> as outputs

; RC<7:6> as inputs

FIGURE 3-9:

PORTC BLOCK DIAGRAM

(PERIPHERAL OUTPUT

OVERRIDE)

PORT/PERIPHERAL Select(2)

Data bus

PORT

TRIS

Data Latch

TRIS Latch

RD TRIS

Schmitt

Trigger

Peripheral Data Out

VDD

VSS

PORT

Peripheral

OE(3)

Peripheral input

I/O

pin(1)

Note 1:

I/O pins have diode protection to VDD and VSS.

Port/Peripheral select signal selects between port

data and peripheral output.

Peripheral OE (output enable) is only activated if

peripheral select is active.

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