Chapter 4
Programming
© National Instruments Corporation
4-5
AT-MIO-16D User Manual
Bit
Name
Description (continued)
5
DMAEN
This bit enables and disables the generation of DMA requests. If
DMAEN is set, a DMA request is generated whenever an A/D
conversion result is available to be read from the A/D FIFO. If
DMAEN is cleared, no DMA request is generated.
4
DAQEN
This bit enables and disables a data acquisition operation that is
controlled by the onboard sample-interval and sample counters. If
DAQEN is set, a software or start trigger starts the counters
(assuming that the counters are programmed and enabled), thereby
initiating a data acquisition operation. If DAQEN is cleared,
software and start triggers are ignored.
3
SCANEN
This bit enables and disables multiple-channel scanning during
data acquisition. If SCANEN is set, alternate analog input
channels are sampled during data acquisition under control of the
mux-gain memory. If SCANEN is cleared, a single analog input
channel is sampled during the entire data acquisition operation.
2
SCANDIV
This bit enables and disables division of the mux-counter clock
during data acquisition. The mux-counter clock controls
sequencing of the mux-gain memory. If SCANDIV is set, the
mux-counter clock is controlled by Counter 1 of the Am9513A
Counter/Timer. If SCANDIV is cleared, the mux-counter clock
generates one pulse per conversion.
1
16*/32CNT
This bit selects the count resolution for the number of A/D
conversions to be performed in a data acquisition operation. If
16*/32CNT is cleared, a 16-bit count mode is selected and Counter
4 of the Am9513A Counter/Timer controls conversion counting. If
16*/32CNT is set, a 32-bit count mode is selected and Counter 4 is
concatenated with Counter 5 to control conversion counting. A
16-bit count mode can be used if the number of A/D sample
conversions to be performed is less than 65,537. A 32-bit count
mode should be used if the number of A/D sample conversions to
be performed is greater than or equal to 65,537.
0
2SCADC*
This bit selects the binary format for the 16-bit data word read
from the A/D FIFO. If 2SCADC* is set, a straight binary format is
used and the data read from the A/D FIFO ranges from 0 to +4,095
decimal (0 to 0FFF hex). This mode is useful if a unipolar input
range is used. If 2SCADC* is cleared, a 16-bit two's complement
mode is used and the data read from the ADC ranges from -2,048
to +2,047 decimal (F800 to 07FF hex). This mode is useful if a
bipolar input range is used.
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