JYTEK NuDAQ PCI-69222, Руководство пользователя

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56 Operation Theory
Digital Waveform Acquisition and Generation
The PCI-69222/PCI-69223 GPI and GPO support digital waveform
generation and digital waveform acquisition. You can sample GPI
or update GPO based on the precision hardware timer.
Digital Waveform Acquisition
The digital data on GPI channels can be acquired by using the
digital waveform acquisition mode. This function is similar with
AI scan acquisition mode.
With periodic sampling clock, you can acquire data based on
the precision hardware time interval. The PCI-69222/PCI-
69223 comes with a dedicated FIFO that stores the sampled
digital data and transfers it to the system memory via DMA.
The GPI is a 16-bit data and the sample clock source can be
configured from an internal timer pacer, internal analog
conversion clock, or external clock. When using an internal
timer pacer as clock source, the GPI supports data transfer
rates of up to 2MHz. The internal analog conversion clock
source can come from AI conversion clock or AO update clock.
The external signal clock source can be set from any of the GPI
[0..7] pins. When the sample clock is from the GPI, the actual
GPI data width is only 15-bit since the external sample clock
signal occupies one bit. Figure 4-28 illustrates the GPI sample clock
routing.
C
N
2 SC
SI
C
ONNE
C
T
OR
G
P
I[
15
..
0]
GP
I
Sa
m
p
le
cl
o
ck
sel
ect
AI Conversion Clock
GPI
Waveform
FIFO
Internal Divided Down Timer
GPI[7..0]
AO Update Clock
GPI Sample Clock
Static GPI