Table of Contents
Advertisement
Port C Pin Assignments
Note
Table 4-3 shows both the port C signal assignments and the terminology
correlation between different documentation sources. The 82C55A terminology
refers to the different 82C55A configurations as modes, whereas NI-DAQ,
ComponentWorks, LabWindows/CVI, and LabVIEW documentation refers to
them as handshaking and no handshaking.
Configuration Terminology
PCI-6023E/
National
6024E/6025E
Instruments
Software
User Manual
Mode 0
No
(Basic I/O)
Handshaking
Mode 1
Handshaking
(Strobed Input)
Mode 1
Handshaking
(Strobed Output)
Mode 2
Handshaking
(Bidirectional
Bus)
*Indicates that the signal is active low.
Subscripts A and B denote port A or port B handshaking signals.
© National Instruments Corporation
In Figure 4-11, port A of one PPI is configured for digital output, and
port B is configured for digital input. Digital input applications include
receiving TTL signals and sensing external device states such as the state
of the switch in Figure 4-11. Digital output applications include sending
TTL signals and driving external devices such as the LED shown in
Figure 4-11.
PCI-6025 Only
The signals assigned to port C depend on how the 82C55A is configured.
In mode 0, or no handshaking configuration, port C is configured as two
4-bit I/O ports. In modes 1 and 2, or handshaking configuration, port C
is used for status and handshaking signals with any leftover lines available
for general-purpose I/O. Table 4-3 summarizes the port C signal
assignments for each configuration. You can also use ports A and B in
different modes; the table does not show every possible combination.
Table 4-3. Port C Signal Assignments
PC7
PC6
I/O
I/O
I/O
I/O
OBF
*
ACK
*
A
A
OBF
*
ACK
*
A
A
Signal Assignments
PC5
PC4
PC3
I/O
I/O
I/O
IBF
STB
*
INTR
A
A
I/O
I/O
INTR
IBF
STB
*
INTR
A
A
4-23
Chapter 4
Signal Connections
PC2
PC1
I/O
I/O
STB
*
IBFB
A
B
B
ACK
*
OBF
*
A
B
B
I/O
I/O
A
PCI-6023E/6024E/6025E User Manual
PC0
I/O
INTR
B
INTR
B
I/O
Hide quick links:
Advertisement
Table of Contents
