Waveform Generation Timing Connections; Wftrig Signal; Update* Signal; General-Purpose Timing Signal Connections - National Instruments PCI-445 Series User Manual

Chapter 4 Signal Connections

Waveform Generation Timing Connections

General-Purpose Timing Signal Connections

PCI-4451/4452/4453/4454 User Manual
of eight pulses in hardware-strobe mode. Figure 4-11 shows the timing for
hardware-strobe mode EXTSTROBE* signal.
V
OH
V
OL

Figure 4-11. EXTSTROBE* Signal Timing

The waveform generation timing signals are WFTRIG and UPDATE*.

WFTRIG Signal

Any PFI pin can receive as an input the WFTRIG signal, which is available
as an output on the PFI6/WFTRIG pin.
As an input, the WFTRIG signal is configured in the edge-detection mode.
You can select any PFI pin as the source for WFTRIG and configure the
polarity selection for either rising or falling edge. The selected edge of the
WFTRIG signal starts the waveform generation for the DACs.
As an output, the WFTRIG signal reflects the trigger that initiates
waveform generation. This is true even if the waveform generation is
externally triggered by another PFI signal. The output is an active high
pulse with a pulse width of 50 to 100 ns. This output is set to
high-impedance at startup.

UPDATE* Signal

The UPDATE* signal is only available as an output on the UPDATE* pin.
The UPDATE* signal reflects the end of a delta-sigma conversion on the
DACs. The output is an active-low pulse with a pulse width of 70 to 100 ns.
This output is set to high-impedance at startup.
The general-purpose timing signals are GPCTR0_SOURCE,
GPCTR0_GATE, GPCTR0_OUT, GPCTR0_UP_DOWN,
GPCTR1_SOURCE, GPCTR1_GATE, GPCTR1_OUT,
GPCTR1_UP_DOWN, and FREQ_OUT.
t
t
w
w
= 600 ns or 5 µs
t
w
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