pico Technology PicoScope 2000 Series Programmer's Guide

API Functions
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PicoScope 2000 Series Programmer's Guide
5.29 ps2000_set_sig_gen_arbitrary
int16_t ps2000_set_sig_gen_arbitrary
(
int16_t handle,
int32_t offsetVoltage,
uint32_t pkToPk,
uint32_t startDeltaPhase,
uint32_t stopDeltaPhase,
uint32_t deltaPhaseIncrement,
uint32_t dwellCount,
uint8_t *arbitraryWaveform,
int32_t arbitraryWaveformSize,
PS2000_SWEEP_TYPE sweepType,
uint32_t sweeps
)
This function programs the signal generator to produce an arbitrary waveform.
The arbitrary waveform generator uses direct digital synthesis (DDS). It maintains a 32-bit
phase accumulator that indicates the present location in the waveform. The top bits of the
phase accumulator are used as an index into a buffer containing the arbitrary waveform. The
remaining bits act as the fractional part of the index, enabling high-resolution control of output
frequency and allowing the generation of lower frequencies.
The generator steps through the waveform by adding a deltaPhase value between 1 and
phaseAccumulatorSize-1 to the phase accumulator every ddsPeriod (1 / ddsFrequency). If the
deltaPhase is constant, the generator produces a waveform at a constant frequency that can
be calculated as follows:
(
) ( )
outputFrequency =
ddsFrequency ×
deltaPhase
phaseAccumulatorSize
×
awgBufferSize
arbitraryWaveformSize
where:
outputFrequency = repetition rate of the complete arbitrary waveform
ddsFrequency = clock rate of phase accumulator (not the same as the DAC
update rate)
deltaPhase = user-specified delta phase value
phaseAccumulatorSize = 2
32
for all models
awgBufferSize = AWG buffer size
arbitraryWaveformSize = length in samples of the user-defined waveform
Parameter
Value
phaseAccumulatorSize
2
32
awgBufferSize
4096
ddsFrequency
48 MHz
ddsPeriod (= 1/ddsFrequency)
20.833 ns (= 1/48 MHz)
It is also possible to sweep the frequency by continually modifying the deltaPhase. This is done
by setting up a deltaPhaseIncrement that the oscilloscope adds to the deltaPhase at
intervals specified by dwellCount.

pico Technology PicoScope 2000 Series Specifications

General

Brand	pico Technology
Model	PicoScope 2000 Series
Category	Test Equipment
Language	English