National Instruments pci-6110e-6111e 用户手册
Chapter 4
Signal Connections
4-32
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National Instruments Corporation
GPCTR1_SOURCE Signal
Any PFI pin can externally input the GPCTR1_SOURCE signal, which
is available as an output on the PFI3/GPCTR1_SOURCE pin.
is available as an output on the PFI3/GPCTR1_SOURCE pin.
As an input, the GPCTR1_SOURCE signal is configured in the
edge-detection mode. You can select any PFI pin as the source for
GPCTR1_SOURCE and configure the polarity selection for either
rising or falling edge.
edge-detection mode. You can select any PFI pin as the source for
GPCTR1_SOURCE and configure the polarity selection for either
rising or falling edge.
As an output, the GPCTR1_SOURCE monitors the actual clock
connected to general-purpose counter 1. This is true even if the source
clock is being externally generated by another PFI. This output is set to
tri-state at startup.
connected to general-purpose counter 1. This is true even if the source
clock is being externally generated by another PFI. This output is set to
tri-state at startup.
Figure 4-29 shows the timing requirements for the GPCTR1_SOURCE
signal.
signal.
Figure 4-29. GPCTR1_SOURCE Signal Timing
The maximum allowed frequency is 20 MHz, with a minimum pulse
width of 10 ns high or low. There is no minimum frequency limitation.
width of 10 ns high or low. There is no minimum frequency limitation.
The 20 MHz or 100 kHz timebase normally generates the
GPCTR1_SOURCE unless you select some external source.
GPCTR1_SOURCE unless you select some external source.
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.
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
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
t
p
t
w
t
w
t
p
t
w
= 50 ns minimum
= 10 ns minimum
PCI_E.book Page 32 Thursday, June 25, 1998 12:55 PM