PIC18F258-ESLASHLSQTP datasheet(106/402 Pages) MICROCHIP

106 / 402 page

PIC18FXX8

DS41159E-page 104

9.5

PORTE, TRISE and LATE

Registers

PORTE is a 3-bit wide, bidirectional port. PORTE has

three pins (RE0/AN5/RD, RE1/AN6/WR/C1OUT and

RE2/AN7/CS/C2OUT) which are individually config-

urable as inputs or outputs. These pins have Schmitt

Trigger input buffers.

Read-modify-write operations on the LATE register,

read and write the latched output value for PORTE.

The corresponding Data Direction register for the port

is TRISE. Setting a TRISE bit (= 1) will make the

corresponding PORTE pin an input (i.e., put the corre-

sponding output driver in a high-impedance mode).

Clearing a TRISE bit (= 0) will make the corresponding

PORTE pin an output (i.e., put the contents of the

output latch on the selected pin).

The TRISE register also controls the operation of the

Parallel Slave Port through the control bits in the upper

half of the register. These are shown in Register 9-1.

When the Parallel Slave Port is active, the PORTE pins

function as its control inputs. For additional details,

refer to Section 10.0 “Parallel Slave Port”.

PORTE pins are also multiplexed with inputs for the A/D

converter and outputs for the analog comparators. When

selected as an analog input, these pins will read as ‘0’s.

Direction bits TRISE<2:0> control the direction of the RE

pins, even when they are being used as analog inputs.

The user must make sure to keep the pins configured as

inputs when using them as analog inputs.

EXAMPLE 9-5:

INITIALIZING PORTE

FIGURE 9-10:

PORTE BLOCK DIAGRAM

Note:

This

port

only

available

the

PIC18F448 and PIC18F458.

CLRF

PORTE

; Initialize PORTE by

; clearing output

; data latches

CLRF

LATE

; Alternate method

; to clear output

; data latches

MOVLW

03h

; Value used to

; initialize data

; direction

MOVWF

TRISE

; Set RE1:RE0 as inputs

; RE2 as an output

; (RE4=0 - PSPMODE Off)

Peripheral Out Select

Data Bus

WR LATE

WR TRISE

Data

Latch

TRIS Latch

RD TRISE

Peripheral Data Out

VDD

VSS

RD PORTE

Peripheral Data In

I/O pin(1)

WR PORTE

RD LATE

Schmitt

Trigger

Note

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

TRIS OVERRIDE

Override Peripheral

RE0

Yes

PSP

RE1

Yes

PSP

RE2

Yes

PSP

TRIS

Override

Peripheral Enable

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