18F8680 datasheet(144/496 Pages) MICROCHIP

144 / 496 page

PIC18F6585/8585/6680/8680

DS30491C-page 142

 2004 Microchip Technology Inc.

10.7

PORTG, TRISG and LATG

Registers

PORTG is a 6-bit wide port with 5 bidirectional pins and

1 unidirectional pin. The corresponding data direction

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 corre-

sponding PORTG 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 register read

and write the latched output value for PORTG.

Pins RG0-RG2 on PORTG are multiplexed with the CAN

peripheral. Refer to Section 23.0 “ECAN Module” for

proper settings of TRISG when CAN is enabled. RG5 is

multiplexed with MCLR/VPP. Refer to Register 24-5 for

more information.

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 output,

while other peripherals override the TRIS bit to make a

pin an input. The user should refer to the corresponding

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 of the TRIS register

without concern due to peripheral overrides.

EXAMPLE 10-7:

INITIALIZING PORT

FIGURE 10-16:

RG0/CANTX1 PIN BLOCK DIAGRAM

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

04h

; Value used to

; initialize data

; direction

MOVWF

TRISG

; Set RG1:RG0 as outputs

; RG2 as input

; RG4:RG3 as inputs

Data Latch

TRIS Latch

RD TRISG

VSS

VDD

RD PORTG

WR TRISG

Data Bus

I/O pin

TXD

ENDRHI

OPMODE2:OPMODE0 = 000

Schmitt

Trigger

RD LATG

WR PORTG or

WR LATG

OPMODE2:OPMODE0 = 000

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

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