User Manual

PIO-48 User Manual

I/O Control Word

Each port may be configured as either Input or Output. This is accomplished by

writing the correct Control Word (CW) to the proper register.

Control Word (X = 0) Hex Value Port Setup

7 6 5 4 3 2 1 0

A B C

1 X X 0 0 X 0 0 80 Out Out Out

1 X X 0 0 X 0 1 81 Out Out In

1 X X 0 0 X 1 0 82 Out In Out

1 X X 0 0 X 1 1 83 Out In In

1 X X 0 1 X 0 0 88 Out Out In

1 X X 0 1 X 0 1 89 Out Out In

1 X X 0 1 X 1 0 8A Out In In

1 X X 0 1 X 1 1 8B Out In In

1 X X 1 0 X 0 0 90 In Out Out

1 X X 1 0 X 0 1 91 In Out In

1 X X 1 0 X 1 0 92 In In Out

1 X X 1 0 X 1 1 93 In In In

1 X X 1 1 X 0 0 98 In Out In

1 X X 1 1 X 0 1 99 In Out In

1 X X 1 1 X 1 0 9A In In In

1 X X 1 1 X 1 1 9B In In In

Interrupt Control

When enabled, interrupts are generated on Port A bit D0.

IRQENn

Interrupt enable 1 = enabled 0 = disabled ( 0 on power up )

IRQCn0

IRQCn1

Interrupt mode select, see table below

n = port number

Interrupt Mode Select Table

IRQCn1 IRQCn0 INT Type

0 0 Low level

0 1 High level

1 0 Falling edge

1 1 Rising edge

Interrupt Read

Reading the INTSTAT port (Base+5) clears any interrupt pending.

IRQST1 (D0) Interrupt status 1 = interrupt pending, 0 = none

IRQST2 (D1) Interrupt status 1 = interrupt pending, 0 = none