Справочник Пользователя для National Instruments NI PCI-6110
Chapter 4
Connecting Signals
© National Instruments Corporation
4-33
GPCTR0_UP_DOWN Signal
This signal can be externally input on the DIO6 pin and is not available as
an output on the I/O connector. The general-purpose counter 0 counts down
when this pin is at a logic low and counts up when it is at a logic high. You
can disable this input so that software controls the up-down functionality
and leaves the DIO6 pin free for general use.
an output on the I/O connector. The general-purpose counter 0 counts down
when this pin is at a logic low and counts up when it is at a logic high. You
can disable this input so that software controls the up-down functionality
and leaves the DIO6 pin free for general use.
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.
available as an output on the PFI3/GPCTR1_SOURCE pin.
As an input, GPCTR1_SOURCE 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.
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, GPCTR1_SOURCE monitors the actual clock connected to
general-purpose counter 1, even if the source clock is being externally
generated by another PFI. This output is set to tri-state at startup.
general-purpose counter 1, even if the source clock is being externally
generated by another PFI. This output is set to tri-state at startup.
Figure 4-30 shows the timing requirements for GPCTR1_SOURCE.
Figure 4-30. 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.
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.
t
w
= 10 ns minimum
t
p
= 50 ns minimum
t
p
t
w
t
w