TDT RZ2, Manual

Page: 194 / 736

4-18 System 3
RV8 Barracuda Processor
2. Determine the number of samples that the circuit runs. The Barracuda can
play out over 4 Gsamples (4*109 samples) on one trigger. Sample
Counter (Low 16) sets the sample number between 0 and 65535 Sample
Counter (High 16) sets it between 65536 and a large number. For
example, to play out 80000 samples the Sample Counter (High 16) would
be set to 1 (65,536) and Sample Counter (Low 16) to 14,464.
3. Load and trigger the circuit.
Sample Count Options
Sample count parameters set the number of samples the circuit will run. The Sample
Counter (Low 16) values are between 0 and 65536 (lower 16-bits of data).
Sample Counter (High 16) values are multiples of 65536. For example, a value of
2 in Sample Counter (High 16) will cause the circuit to run for 131,072 samples.
If the system needed to run for 200,000 samples you would set Sample Counter
(High 16) = 3 (196,608 samples) and Sample Counter (Low 16) = 3,392.
Sample count is only used when in trigger mode. At all other times the circuit is
free running.
Sample Counter (Low 16) = the lower 16bits of the sample counter (0-65535)
Sample Counter (High 16) = the upper 16bits of the counter. A value of 1 in
Sample Counter (High 16) = 65536.
Logic
User selects whether a high voltage on a digital line is a logical 1 or logical 0 on
the Barracuda.
The default state for a high voltage on a digital line is 1 (high true). Setting
InLogic = 1 inverts the logic (low true) and makes a high input voltage produce a
0 and a low input voltage produce a 1. Similarly, when setting OutLogic = 1, a high
voltage on a digital output line will produce a 0 and a low voltage will produce a 1.
Software Control
The Barracuda has two modes: free-run and trigger. In free-run mode the circuit is
always running and signals are constantly generated, acquired, and filtered. In the
trigger mode the circuit runs for a set length each time it is triggered. The
advantage of the trigger mode is that some circuit design is simplified. The example
below shows two circuits that present a tone burst of 100 milliseconds. The first
circuit works under the free-run mode and the second with trigger.
Free ‐ Run Mode