Справочник Пользователя для National Instruments PCI-DIO-96

Chapter 6

Programming

 National Instruments Corporation

6-19

PCI-DIO-96 User Manual

2-0

I/O

Input/Output—Use these bits for general-purpose 

I/O lines if group B is configured for mode 0. If 
group B is configured for mode 1, refer to the bit 
explanations shown in the preceding mode 1 
sections.

Figure 6-8 shows the port C pin assignments on the digital I/O 
connector when port C is configured for mode 2. Notice that the status 
of STBA* and the status of ACKA* are not included in the port C status 
word.

Figure 6-8.  Port C Pin Assignments on I/O Connector when Port C is 

Configured for Mode 2

The following example shows how to configure PPI A for mode 2 input 
and output.

Write (8255Cnfg, 0xC0)

Set mode 2 — port A 

is bidirectional

Loop until OBFA (PC7) is set, indicating that the 

data last written to port A 

has been read

Write (PortA, Data)

Write data to port A

Loop until IBFA (PC5) is set, indicating that data is

available in port A to be read

Read (PortA)

Now, read the data from port A

PC7

OBFA*

PC6

ACKA*

PC5

IBFA

PC4

STBA*

PC3

INTRA

PC2

#

PC1

#

PC0

#

Group A

Group B

#   The three port C lines associated with group B function based on the 

mode selected for group B; that is, if group B is configured for mode 0, 

PC<2..0> function as general-purpose I/O, but if group B is configured 

for mode 1 input or output, PC<2..0> function as handshaking lines as 

shown in the preceding mode 1 sections.