PIC18LC658T-ESLASHCL datasheet(109/366 Pages) MICROCHIP

109 / 366 page

 2000 Microchip Technology Inc.

Advanced Information

DS30475A-page 109

PIC18CXX8

9.0

PARALLEL SLAVE PORT

The Parallel Slave Port is an 8-bit parallel interface for

transferring data between the PIC18CXX8 device and

an external device.

PORTD operates as an 8-bit wide Parallel Slave Port,

or microprocessor port when control bit PSPMODE

(PSPCON register) is set. In Slave mode, it is asyn-

chronously readable and writable by the external world

through RD control input pin RE0/RD and WR control

input pin RE1/WR.

It can directly interface to an 8-bit microprocessor data

bus. The external microprocessor can read or write the

PORTD latch as an 8-bit latch. Setting bit PSPMODE

enables port pin RE0/RD to be the RD input, RE1/WR

to be the WR input and RE2/CS to be the CS (chip

select) input. For this functionality, the corresponding

data direction bits of the TRISE register (TRISE<2:0>)

must be configured as inputs (set).

A write to the PSP occurs when both the CS and WR

lines are first detected low. A read from the PSP occurs

when both the CS and RD lines are first detected low.

The PORTE I/O pins become control inputs for the

microprocessor port when bit PSPMODE (PSPCON

that the TRISE<2:0> bits are set (pins are configured

as digital inputs). In this mode, the input buffers are

TTL.

FIGURE 9-1:

PORTD AND PORTE BLOCK

DIAGRAM

(PARALLEL SLAVE PORT)

Data Bus

WR LATD

RDx Pin

RD PORTD

One bit of PORTD

Set Interrupt Flag

PSPIF (PIR1<7>)

Read

Chip Select

Write

TTL

WR PORTD

RD LATD

Data Latch

Note:

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

PIC18LC658T-E/CL Datasheet(PDF) 109 Page - Microchip Technology

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