National Instruments 3.21E+04 Manual De Usuario
Chapter 4 Signal Connections
National Instruments Corporation
4-49
AT-MIO/AI E Series User Manual
Figure 4-34 shows the timing requirements for the GPCTR1_SOURCE
signal.
signal.
Figure 4-34. 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.
width 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.
As an output, the GPCTR1_GATE signal monitors the actual gate
signal connected to general-purpose counter 1. This is true even if the
gate is being externally generated by another PFI. This output is set to
tri-state at startup.
signal connected to general-purpose counter 1. This is true even if the
gate is being externally generated by another PFI. This output is set to
tri-state at startup.
t
p
t
w
t
w
t
p
t
w
= 50 ns minimum
= 23 ns minimum