Справочник Пользователя для National Instruments PC-DIO-24

Main() {

#define BASE_ADDRESS

0x210

/* Board located at address 210. */

#define PORTAoffset

0x00

/* Offset for port A */

#define PORTBoffset

0x01

/* Offset for port B */

#define PORTCoffset

0x02

/* Offset for port C */

#define CNFGoffset

0x03

/* Offset for CNFG   */

register unsigned int porta, portb, portc, cnfg;
char valread;

/* Variable to store data read from a 

port */

/*  Calculate register addresses. */

porta = BASE_ADDRESS + PORTAoffset;
portb = BASE_ADDRESS + PORTBoffset;
portc = BASE_ADDRESS + PORTCoffset;
cnfg  = BASE_ADDRESS + CNFGoffset;

/* EXAMPLE 1–port A input */

outp(cnfg,0xB0);

/* Port A is an input in mode 1. */

while (!(inp(portc) & 0x20));

/* Wait until IBFA is set, indicating that

data has been loaded in port A. */

valread = inp(porta);

/* Read the data from port A. */

/* EXAMPLE 2–port B input */

outp(cnfg,0x86);

/* Port B is an input in mode 1. */

while (!(inp(portc) & 0x02));

/* Wait until IBFB is set, indicating that

data has been loaded in port B. */

valread = inp(portb);
}

The control word written to the CNFG Register to configure port A for output in mode 1 is
shown as follows.  Bits PC4 and PC5 of port C can be used as extra input or output lines when
port A uses mode 1 output.

1

0

1

0

1/0

X

X

X

7

6

5

4

3

2

1

0

 

 1 = input

 0 = output

Port C bits PC4 and PC5