National Instruments NI PCI-6110 - Manual (Page 61)

Chapter 4 Connecting Signals
© National Instruments Corporation 4-31 NI PCI-6110/6111 User Manual
GPCTR0_SOURCE Signal
Any PFI pin can externally input the GPCTR0_SOURCE signal, which is
available as an output on the PFI8/GPCTR0_SOURCE pin.
As an input, GPCTR0_SOURCE is configured in the edge-detection mode.
You can select any PFI pin as the source for GPCTR0_SOURCE and
configure the polarity selection for either rising or falling edge.
As an output, GPCTR0_SOURCE reflects the actual clock connected to
general-purpose counter 0, even if another PFI is externally inputting the
source clock. This output is set to high-impedance at startup.
Figure 4-27 shows the timing requirements for GPCTR0_SOURCE.
Figure 4-27. GPCTR0_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.
The 20 MHz or 100 kHz timebase normally generates the
GPCTR0_SOURCE signal unless you select some external source.
GPCTR0_GATE Signal
Any PFI pin can externally input the GPCTR0_GATE signal, which is
available as an output on the PFI9/GPCTR0_GATE pin.
As an input, GPCTR0_GATE is configured in the edge-detection mode.
You can select any PFI pin as the source for GPCTR0_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 actions such as
starting and stopping the counter, generating interrupts, and saving the
counter contents.
t
w
= 10 ns minimum
t
p
= 50 ns minimum
t
p
t
w
t
w