Chapter 4
Signal Connections
4-30
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Either the 20 MHz or 100 kHz internal timebase generates the SISOURCE
signal unless you select some external source. Figure 4-23 shows the timing
requirements for the SISOURCE signal.
Figure 4-23.
SISOURCE Signal Timing
Waveform Generation Timing Connections
The analog group defined for your device is controlled by WFTRIG,
UPDATE*, and UISOURCE.
WFTRIG Signal
Any PFI pin can externally 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. The update
interval (UI) counter is started if you select internally generated UPDATE*.
As an output, the WFTRIG signal reflects the trigger that initiates
waveform generation. This is true even if the waveform generation is being
externally triggered by another PFI. The output is an active high pulse with
a pulse width of 50 to 100 ns. 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
