Chapter 4
Signal Connections
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National Instruments Corporation
4-37
GPCTR1_GATE Signal
Any PFI pin can externally input the GPCTR1_GATE signal, which is
available as an output on the PFI4/GPCTR1_GATE pin.
As an input, the GPCTR1_GATE signal is configured in edge-detection
mode. You can select any PFI pin as the source for GPCTR1_GATE and
configure the polarity selection for either rising or falling edge. You can use
the gate signal in a variety of different applications to perform such actions
as starting and stopping the counter, generating interrupts, saving the
counter contents, and so on.
As an output, the GPCTR1_GATE signal monitors the actual gate signal
connected to general-purpose counter 1. This is true even if the gate is
being externally generated by another PFI. This output is set to tri-state at
startup. Figure 4-33 shows the timing requirements for the
GPCTR1_GATE signal.
Figure 4-33.
GPCTR1_GATE Signal Timing in Edge-Detection Mode
Rising-Edge
Polarity
Falling-Edge
Polarity
t
w
t
w
= 10 ns minimum