Chapter4 SignalConnections
6023E/6024E/6025EUser Manual 4-46 ni.com
GPCTR1_SOURCE Signal
AnyPFI pin can extern ally 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 selectany PFI pin as thesource for GPCTR1_SOURCE and
configure the polarity selection for either rising or falling edge.
Asan output, the GPCTR1_SOURCE monitors the actual clock connected
to general-purpose counter 1. This is true evenif the source clock is
externally generated byanoth er PFI. This output is set to high impedance
atstartup.
Figure 4-38 showsthe timing requirements for the GPCTR1_SOURCE
signal.
Figure4-38. GPCTR1_SOURCE Signal Timing
Themaximum allowed frequency is 20 MH z, with a minimum pulse width
of 23 ns high or low.There is no minimum frequency limitation.
The 20M Hz or100 kHz timebase normally generates the
GPCTR1_SOURCE unless you select some externalsource.
GPCTR1_GATE Signal
Any PFIpin can ext ernally input the GPCTR1_GATE signal, which is
available as an output on the PFI4/GPCTR1_GATE pin.
As aninput, the GPCTR1_GATE signal is configured in edge-detection
mode. Youcan select any PFI pin as the source for GPCTR1_GATE and
configurethe polarity selection for either rising or falling edge. You can use
thegate signal in a variety of different applications to perform such actions
asstartin g and stopping the counter,generating interrupts, saving the
counter contents, and so on.
tp
twtw
tp
tw
=50 ns minimum
=23 ns minimum