PIC18F6X2X datasheet(126/386 Pages) MICROCHIP

126 / 386 page

PIC18F6X2X/8X2X

DS39612A-page 124

Advance Information

 2003 Microchip Technology Inc.

10.8

PORTH, LATH, and TRISH

Registers

PORTH is an 8-bit wide, bi-directional I/O port. The cor-

responding data direction register is TRISH. Setting a

TRISH bit (= 1) will make the corresponding PORTH

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

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

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

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

Read-modify-write operations on the LATH register,

read and write the latched output value for PORTH.

Pins RH7:RH4 are multiplexed with analog inputs

AN15:AN12. Pins RH3:RH0 are multiplexed with the

system bus as the external memory interface; they are

the high order address bits A19:A16. By default, pins

RH7:RH4 are enabled as A/D inputs and pins

RH3:RH0 are enabled as the system address bus.

inputs. Register MEMCON configures RH3:RH0 as I/O

or system bus pins.

EXAMPLE 10-8:

INITIALIZING PORTH

FIGURE 10-18:

RH3:RH0 PINS BLOCK

DIAGRAM IN I/O MODE

FIGURE 10-19:

RH7:RH4 PINS BLOCK

DIAGRAM IN I/O MODE

Note:

PORTH is available only on PIC18F8X2X

devices.

Note 1: On

Power-on

Reset,

PORTH

pins

RH7:RH4 default to A/D inputs and read

as ‘0’.

2: On

Power-on

Reset,

PORTH

pins

RH3:RH0 default to system bus signals.

CLRF

PORTH

; Initialize PORTH by

; clearing output

; data latches

CLRF

LATH

; Alternate method

; to clear output

; data latches

MOVLW

0Fh

;

MOVWF

ADCON1

;

MOVLW

0CFh

; Value used to

; initialize data

; direction

MOVWF

TRISH

; Set RH3:RH0 as inputs

; RH5:RH4 as outputs

; RH7:RH6 as inputs

Data

Bus

WR LATH

WR TRISH

RD PORTH

Data Latch

TRIS Latch

RD TRISH

Schmitt

Trigger

Input

Buffer

I/O pin(1)

RD LATH

PORTH

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

Data

Bus

WR LATH

WR TRISH

RD PORTH

Data Latch

TRIS Latch

RD TRISH

Schmitt

Trigger

Input

Buffer

I/O pin(1)

RD LATH

PORTH

To A/D Converter

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

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