Chapter 4
Programming
© National Instruments Corporation
4-23
AT-DIO-32F User Manual
Port B Register
The Port B Register contains eight bits that connect to the digital I/O connector and can either be
read from or written to.
Address:
Base a 07 (hex)
Type:
Read-and-write
Word Size:
8-bit
Bit Map:
7
6
5
4
3
2
1
0
DIOB7
DIOB6
DIOB5
DIOB4
DIOB3
DIOB2
DIOB1
DIOB0
When Port B is configured as a write port, writing data to this register latches the data into Port B
and sends the data out on Port B. Reading Port B when it is in write mode returns the value that
is currently driven on the port. If the DBLBUFB bit in the CFG3 Register is set, the data written
to Port A is stored in the buffer. However, this data is not dumped to the I/O connector until the
active REQ1 level or pulse is received. During an active REQ1 level or pulse, the data is
dumped to the I/O connector.
When Port B is configured as a read port, reading Port B returns the current data at Port B. If the
DBLBUFB bit in the CFG3 Register is set, data is latched into Port B on the active level or
active edge of REQ1. In level mode, data is latched during the active level of REQ1 until REQ1
is inactive. In pulse mode, data is latched on the active edge of REQ1 until the data is read from
the port.
Only 8-bit transfers can be performed on Port B.
8-Bit Write or Read from Port B
Port B
7
6
5
4
3
2
1
0
Содержание AT-DIO-32F
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