PIC18F442-ESLASHP datasheet(102/332 Pages) MICROCHIP

102 / 332 page

PIC18FXX2

DS39564B-page 100

 2002 Microchip Technology Inc.

9.6

Parallel Slave Port

The Parallel Slave Port is implemented on the 40-pin

devices only (PIC18F4X2).

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

or microprocessor port when control bit, PSPMODE

(TRISE<4>) is set. It is asynchronously 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). The A/D port config-

uration bits PCFG2:PCFG0 (ADCON1<2:0>) must be

set, which will configure pins RE2:RE0 as digital I/O.

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 (TRISE<4>)

is set. In this mode, the user must make sure that the

TRISE<2:0> bits are set (pins are configured as digital

inputs), and the ADCON1 is configured for digital I/O.

In this mode, the input buffers are TTL.

FIGURE 9-10:

PORTD AND PORTE

BLOCK DIAGRAM

(PARALLEL SLAVE

PORT)

FIGURE 9-11:

PARALLEL SLAVE PORT WRITE WAVEFORMS

Data Bus

WR LATD

RDx

RD PORTD

One bit of PORTD

Set Interrupt Flag

PSPIF (PIR1<7>)

Read

Chip Select

Write

Note: I/O pin has protection diodes to VDD and VSS.

TTL

PORTD

RD LATD

Data Latch

TRIS Latch

IBF

OBF

PSPIF

PORTD<7:0>

PIC18F442-E/P Datasheet(PDF) 102 Page - Microchip Technology

PIC18F442-E/P Datasheet(HTML) 102 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL