PIC18F6X2X datasheet(124/386 Pages) MICROCHIP

124 / 386 page

PIC18F6X2X/8X2X

DS39612A-page 122

Advance Information

 2003 Microchip Technology Inc.

10.7

PORTG, TRISG and LATG

Registers

PORTG is a 6-bit wide port with 5 bi-directional pins

(RG0:RG4) and one optional input only pin (RG5). The

corresponding Data Direction register is TRISG. Setting

a TRISG bit (= 1) will make the corresponding PORTG

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

a high-impedance mode). Clearing a TRISG bit (= 0)

will make the corresponding PORTC pin an output (i.e.,

put the contents of the output latch on the selected pin).

The Data Latch register (LATG) is also memory

mapped. Read-modify-write operations on the LATG

PORTG.

PORTG is multiplexed with both CCP and USART

functions (Table 10-13). PORTG pins have Schmitt

Trigger input buffers.

When enabling peripheral functions, care should be

taken in defining TRIS bits for each PORTG 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. The user should refer to the corre-

sponding peripheral section for the correct TRIS bit

settings.

The pin override value is not loaded into the TRIS reg-

ister. This allows read-modify-write operations of the

TRIS register without concern due to peripheral

overrides.

The sixth pin of PORTG (MCLR/VPP/RG5) is a digital

input pin. Its operation is controlled by the MCLRE

configuration

bit

Configuration

(CONFIG3H<7>).

its

default

configuration

(MCLRE = 1), the pin functions as the device Master

Clear input. When selected as a port pin (MCLRE = 0),

it functions as an input only pin; as such, it does not

have TRISG or LATG bits associated with it.

In either configuration, RG5 also functions as the

programming voltage input during device programming.

EXAMPLE 10-7:

INITIALIZING PORTG

FIGURE 10-16:

PORTG BLOCK DIAGRAM (PERIPHERAL OUTPUT OVERRIDE)

Note:

On a Power-on Reset, these pins are

configured as digital inputs.

Note 1: On a Power-on Reset, RG5 is enabled as

a digital input only if Master Clear

functionality is disabled (MCLRE = 0).

2: If the device Master Clear is disabled,

verify that either of the following is done to

ensure proper entry into ICSP mode:

a.) disable low voltage programming

(CONFIG4L<2> = 0); or

b.) make certain that RB5/KBI1/PGM is

held low during entry into ICSP.

CLRF

PORTG

;

Initialize PORTG by

; clearing output

; data latches

CLRF

LATG

; Alternate method

; to clear output

; data latches

MOVLW

0x04

;

Value used to

; initialize data

; direction

MOVWF

TRISG

;

Set RG1:RG0 as outputs

; RG2 as input

;

RG4:RG3 as inputs

PORTG/Peripheral Out Select

Data Bus

WR LATG

WR TRISG

Data Latch

TRIS Latch

RD TRISG

Peripheral Data Out

VDD

VSS

RD PORTG

Peripheral Data In

I/O pin(1)

WR PORTG

RD LATG

Schmitt

Trigger

TRIS

Override

Peripheral Output

Logic

TRIS OVERRIDE

Override

Peripheral

RG0

Yes

CCP3 I/O

RG1

Yes

USART1 Async Xmit,

Sync Clock

RG2

Yes

USART1 Async Rcv,

Sync Data Out

RG3

Yes

CCP4 I/O

RG4

Yes

CCP5 I/O

Enable(2)

Note 1: I/O pins have diode protection to VDD

and VSS.

2: Peripheral output enable is only active

if peripheral select is active.

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