National Instruments PC-DIO-96 Manual Do Utilizador

porta = BASE_ADDRESS + APORTAoffset;
portb = BASE_ADDRESS + APORTBoffset;
portc = BASE_ADDRESS + APORTCoffset;
cnfg  = BASE_ADDRESS + ACNFGoffset;

/* EXAMPLE 1*/

outp(cnfg,0x80);

/* Ports A, B, and C are outputs. */

outp(porta,0x12);

/* Write data to port A. */

outp(portb,0x34);

/* Write data to port B. */

outp(portc,0x56);

/* Write data to port C. */

/* EXAMPLE 2*/

outp(cnfg,0x90);

/* Port A is input; ports B and C are

outputs. */

outp(portb,0x22);

/* Write data to port B. */

outp(portc,0x55);

/* Write data to port C. */

valread = inp(porta);

/* Read data from port A. */

/* EXAMPLE 3 */

outp(cnfg,0x82);

/* Ports A and C are outputs; port B 

is an input. */

/* EXAMPLE 4 */

outp(cnfg,0x89);

/* Ports A and B are outputs; port C 

is an input. */

}

In mode 1, the digital I/O bits are divided into two groups:  group A and group B.  Each of these
groups contains one 8-bit port and one 4-bit control/data port.  The 8-bit port can be either an
input or an output port, and the 4-bit port is used for control and status information for the 8-bit
port.  The transfer of data is synchronized by handshaking signals in the 4-bit port.

The control word written to the CNFG Register to configure port A for input in mode 1 is shown
as follows.  Bits PC6 and PC7 of port C can be used as extra input or output lines.

D2

D1

D0

D3

D7

D6

D5

D4

1 = input
0 = output

Port C bits PC6 and PC7

1

0

1/0

X

X

X

1

1