National Instruments AT E Series GPCTR0

Chapter4 ConnectingSignals

©NationalInstruments Corporation 4-45 ATE Series User Manual

As ano utput, the GPCTR0_SOURCE signal reflects the actual clock

connected to general-purpose counter 0, evenif anot her PFI is externally

inputting the source clock. This output is set to high-impedance at startup.

Figure 4-31 showsthe timing requirements for the GPCTR0_SOURCE

signal.

Figure4-31. GPCTR0_SOURCE Signal Timing

Themaximum allowed frequency is 20 MHz, 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

GPCTR0_SOURCE signal unless you select some external source.

GPCTR0_GATE Signal

Any PFIpin can ext ernally input the GPCTR0_GATE signal, which is

available as an output on the PFI9/GPCTR0_GATE pin.

Asan input, the GPCTR0_GATE signal is configured in the edge-detection

mode. Youcan select any PFI pin as the source for GPCTR0_GATE and

configurethe polarity selection for either rising or falling edge. You can use

thegate signal in a variety of different applications to perform actions such

asstartin g and stopping the counter,generating interrupts, saving the

counter contents, and so on.

As ano utput, the GPCTR0_GATEsignal reflects the actual gate signal

connectedto general-purpose counter 0, even if the gate is being externally

generated byan other PFI. This output is set to high-impedance at startup.

tw=23 ns minimum

tp=50 ns minimum