National Instruments 6023E ユーザーズマニュアル
Chapter 4
Signal Connections
4-46
ni.com
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. 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.
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.
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
externally generated by another PFI. This output is set to high impedance
at startup.
to general-purpose counter 1. This is true even if the source clock is
externally generated by another PFI. This output is set to high impedance
at startup.
Figure 4-38 shows the timing requirements for the GPCTR1_SOURCE
signal.
signal.
Figure 4-38. GPCTR1_SOURCE Signal Timing
The maximum allowed frequency is 20 MHz, with a minimum pulse width
of 23 ns high or low. There is no minimum frequency limitation.
of 23 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 actions
as starting and stopping the counter, generating interrupts, saving the
counter contents, and so on.
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.
t
p
t
w
t
w
t
p
t
w
= 50 ns minimum
= 23 ns minimum