
Chapter4 ConnectingSignals
ATE Series User Manual 4-44 ni.com
UISOURCE SignalAny PFIpin can ext ernally input the UISOURCE signal, which is not
available as an output on the I/O connector. The UI counter uses the
UISOURCE signal as a clockt o time the generation of the UPDATE*
signal. You must configure the PFI pin you select as the source for the
UISOURCE signal in the level-detection mode. You can configure the
polarity selection forthe PFIpin for either active high or active low.
Figure 4-30 shows the timing requirements for the UISOURCE signal.
Figure4-30. UISOURCE Signal Timing
Themaximum allowed frequency is 20 MHz, with a minimum pulse width
of 23 ns high or low.There is no minimum frequency limitation.
Either the 20 MHz or 100 kHz internal timebase normally generates the
UISOURCE signal unlessyou select some external source.
General-Purpose Timing Signal ConnectionsThe general-purpose timing signals are GPCTR0_SOURCE,
GPCTR0_GATE, GPCTR0_OUT, GPCTR0_UP_DOWN,
GPCTR1_SOURCE, GPCTR1_GATE, GPCTR1_OUT,
GPCTR1_UP_DOWN, and FREQ_OUT.
GPCTR0_SOURCE SignalAnyPFI pin can extern ally input the GPCTR0_SOURCE signal, which is
available as an output on the PFI8/GPCTR0_SOURCE pin.
As ani nput, the GPCTR0_SOURCE signal is configured in the
edge-detectionm ode. Youcan select any PFI pin as the source for
GPCTR0_SOURCE and configurethe polarity selection for either rising
or falling edge.
tp=50 ns minimum
tw=23 ns minimum
tw
tw
tp