JYTEK USB-61210, User Manual

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Operation & Calibration 25
Figure 3-4: Configuring Different Sampling Rates
Sampling Rate Control with External Conversion Strobe Clock
The A/D conversion clock can be provided by external strobe clock via
CONV pin. The valid frequency of external clock is from DC to 2 MHz and
the minimum pulse width is 225ns.
Analog Input Triggering
The USB-61210 supports flexible trigger sources for analog input func -
tionality. The trigger source can originate with software command,
external analog, or external digital signal in continuous analog input
mode. Users can configure the trigger source and trigger mode by soft -
ware.
3.1.3 Trigger Sources
Software Triggering
This trigger mode requires no external trigger source. The trigger asserts
immediately following execution of the specified function calls to begin
the operation.
External Analog Triggering
The analog multiplexer can select one input channel as the analog
trigger source. That is, one of 4 input channels in differential mode can
be selected as the analog trigger source. An external analog trigger
occurs when the analog trigger signal crosses above (above high) or
below (below low) the pre-defined voltage level. The range of trigger
level is the full-scale range of the selected input channel and the
resolution is 16-bit.
Below-Low Analog Triggering
In below-low analog triggering, as shown, the trigger signal is gener -
ated when the input analog signal is less than the Low_Threshold