ADLINK PXI-2502 - Manual (Page 41)

Operation Theorem
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size of a single waveform were larger than that of the FIFO, it needs to be
intermittently loaded from the host PC’s memory via DMA, thus PCI
bandwidth would be occupied.
If the value specified in UC_counter is smaller than the sample size of the
waveform patterns, the waveform will be generated piece-wisely. For
example, if users defined a 16-sample sine wave and set the UC_counter
to 2, the generated waveform will be a 1/8-cycle sine wave for every
waveform period. In other words, a complete sine wave will be generated
for every 8-iterations. If value specified in UC_counter is larger than the
sample size of waveform LUT, say, 32; the generated waveform will be a
2-cycle sine wave for every waveform period.
In conjunction with different trigger modes and counter setups, users can
manipulate a single waveform to generate different, more complex wave-
forms. For more information, please refer to Appendix A.
(UC _Counter=4, IC_Counter=3, DLY2_Counter=0)
4 update counts, 3 iterations
DAWR
WFG_in_progress
Operation start
Trigger
Output Waveform
0
2
4
A single waveform
Figure 4.2.7 Finite iterative waveform generation with Post-trigger
(Assuming the digital codes in the FIFO are 2V, 4V, 2V, 0V)
(UC _Counter=4, IC_Counter=disabled, DLY2_Counter=disabled)
4 update counts, infinite iterations
DAWR
WFG_in_progress
Operation start
Trigger
Output Waveform
waveform generation
won’t stop until a stop
trigger is asserted
0
2
4
Figure 4.2.8 Infinite iterative waveform generation with Post-trigger
(Assuming the digital codes in the FIFO are 2V, 4V, 2V, 0V)