National Instruments PC-DIO-96 Manual de usuario descargar pdf (Pagina 54)

PC-DIO-96 User Manual 4-16 © National Instruments Corporation

Bit Name Description (continued)

2 INTEB Interrupt Enable Bit for Port B—Setting this bit enables interrupts

from port B of the 82C55A. This bit is controlled by

setting/resetting PC2.

1 OBFB* Output Buffer for Port B—A low setting indicates that the CPU

has written data to port B.

0 INTRB Interrupt Request Status for Port B—When INTEB and OBFB* are

high, this bit is high, indicating that an interrupt request is pending

for port B.

At the digital I/O connector, port C has the following pin assignments when in mode 1 output.

Notice that the status of ACKA* and the status of ACKB* are not included when port C is read.

PC7

PC6

PC5

PC4

PC3

PC2

PC1

PC0

OBFA*

ACKA*

I/O

INTRA

ACKB*

OBFB*

INTRB

Group A

Group B

Mode 1 Output Programming Example

The following example shows how to configure PPI A for various combinations of mode 1

output. This code is strictly an example and is not intended to be used without modification in a

practical situation.

Main() {

#define BASE_ADDRESS 0x180 /* Board located at address 180 */

#define APORTAoffset 0x00 /* Offset for PPI A, port A */

#define APORTBoffset 0x01 /* Offset for PPI A, port B */

#define APORTCoffset 0x02 /* Offset for PPI A, port C */

#define ACNFGoffset 0x03 /* Offset for PPI A, CNFG */

unsigned int porta, portb, portc, cnfg;

char valread; /* Variable to store data read from a

port */

/* Calculate register addresses */

porta = BASE_ADDRESS + APORTAoffset;

portb = BASE_ADDRESS + APORTBoffset;

portc = BASE_ADDRESS + APORTCoffset;

cnfg = BASE_ADDRESS + ACNFGoffset;

/* EXAMPLE 1–port A output */

1 2 ... 49 50 51 52 53 54 55 56 57 58 59 ... 104 105

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National Instruments PC-DIO-96 Manual de usuario Pagina 54

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