Advantech PCI-1757UP Especificaciones descargar pdf (Pagina 21)

Chapter 3 Function Description 17

3.1 Overview

This chapter describes the operating characteristics of the PCI-1757UP.

The driver software provided allows a user to access all of the card's

functions without register level programming. Please see the User's

Manual for the driver bundled with this card for more information. For

users who prefer to implement their own bit-level programming to drive

the card's functions, information useful for making such a program is

included in this chapter.

3.2 Digital I/O Ports

Introduction

The PCI-1757UP emulates one 8255 programmable peripheral interface

(PPI) chips in mode 0, but with higher driving capability than a standard

8255 chip. Each of the 8255 chips has 24 programmable I/O pins that

are divided into three 8-bit ports, designated PA, PB and PC. Each port

can be programmed as an input or an output port. The I/O pins in port A

are designated PA0, PA1,..., PA7; the pins in port B are designated PB0,

PB1,..., PB7, etc. These port names are used both in this manual and in

the software library. Refer to Section 2.4, Pin Assignments.

8255 Mode 0

The basic functions of 8255 mode 0 include:

• Two 8-bit I/O ports - port A (PA) and port B (PB)

• Port C is divided into two nibble -wide (4-bit) I/O ports: PC upper and

PC lower

• Any port can be used for either input or output.

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Advantech PCI-1757UP Especificaciones Pagina 21