Pfi Filters - National Instruments DAQ X Series User Manual

PFI Filters

You can enable a programmable debouncing filter on each PFI, RTSI,
PXI_STAR, or PXIe-DSTAR<A,B> signal. When the filters are enabled,
your device samples the input on each rising edge of a filter clock. X Series
devices use an onboard oscillator to generate the filter clock.
The following is an example of low to high transitions of the input signal.
High-to-low transitions work similarly.
Assume that an input terminal has been low for a long time. The input
terminal then changes from low to high, but glitches several times. When
the filter clock has sampled the signal high on N consecutive edges, the low
to high transition is propagated to the rest of the circuit. The value of N
depends on the filter setting; refer to Table 8-1.
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PFI 0 PFI 2
Source Source
Figure 8-2. PFI Input Signal Connections
8-5
Chapter 8
PFI 0
PFI 2
D GND
I/O Connector
X Series Device
X Series User Manual
PFI