PIC16F72SLASHML datasheet(27/136 Pages) MICROCHIP

27 / 136 page

 2002 Microchip Technology Inc.

DS39597B-page 25

PIC16F72

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-modify-

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 3-3:

INITIALIZING PORTC

FIGURE 3-5:

PORTC BLOCK DIAGRAM

(PERIPHERAL OUTPUT

OVERRIDE)

BANKSEL

PORTC

; Select Bank for PORTC

CLRF

PORTC

; Initialize PORTC by

; clearing output

; data latches

BANKSEL

TRISC

; Select Bank for TRISC

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

Port/Peripheral Select(1)

Data

Port

TRIS

Data Latch

TRIS Latch

RD TRIS

Schmitt

Trigger

Peripheral Data Out

VDD

VSS

Port

Peripheral

OE(2)

Peripheral Input

Note

Port/Peripheral select signal selects

between port data and peripheral output.

2: Peripheral OE (output enable) is only

activated if peripheral select is active.

VSS

I/O

VDD

Bus

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