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Chapter 2
Configuration and Installation
© National Instruments Corporation
2-45
AT-MIO-16D User Manual
Table 2-11. Port C Signal Assignments
Programming
Mode
Group A
Group B
PC7
PC6
PC5
PC4
PC3
PC2
PC1
PC0
Mode 0
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
Mode 1 Input
I/O
I/O
IBFA
STBA*
INTRA
STBB*
IBFBB
INTRB
Mode 1 Output
OBFA*
ACKA*
I/O
I/O
INTRA
ACKB*
OBFB*
INTRB
Mode 2
OBFA*
ACKA*
IBFA
STBA*
INTRA
I/O
I/O
I/O
* Indicates that the signal is active low.
Timing Specifications
This section lists the timing specifications for handshaking with the DIO-24 circuitry. The
handshaking lines STB* and IBF synchronize input transfers. The handshaking lines OBF* and
ACK* synchronize output transfers.
The following signals are used in the timing diagrams that follow.
Name
Type
Description
STB*
input
Strobe Input
A low signal on this handshaking line loads data into the input latch.
IBF
output
Input Buffer Full
A high signal on this handshaking line indicates that data has been
loaded into the input latch. This is an input acknowledge signal.
ACK*
input
Acknowledge Input
A low signal on this handshaking line indicates that the data written
from the selected port has been accepted. This signal is a response
from the external device that it has received the data from the AT-
MIO-16D.
OBF*
output
Output Buffer Full
A low signal on this handshaking line indicates that data has been
written from the selected port.
INTR
output
Interrupt Request
This signal becomes high when the 82C55A is requesting service
during a data transfer. The appropriate DIO interrupt enable bits
must be set to generate this signal.
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