User manual

ManualsBrandsPICO ManualsLaboratory Test EquipmentPC scope module Scope 6403D 350 MHz 8-channel 5 null 1 null 8 Bit Digital storage (DSO), Function generator, S

Programming with the PicoScope 6000 Series72

3.9.43

ps6000SetSigGenArbitrary

PICO_STATUS ps6000SetSigGenArbitrary

(

short handle,

long offsetVoltage,

unsigned long pkToPk

unsigned long startDeltaPhase,

unsigned long stopDeltaPhase,

unsigned long deltaPhaseIncrement,

unsigned long dwellCount,

short * arbitraryWaveform,

long arbitraryWaveformSize,

PS6000_SWEEP_TYPE sweepType,

PS6000_EXTRA_OPERATIONS operation,

PS6000_INDEX_MODE indexMode,

unsigned long shots,

unsigned long sweeps,

PS6000_SIGGEN_TRIG_TYPE triggerType,

PS6000_SIGGEN_TRIG_SOURCE triggerSource,

short extInThreshold

)

This function programs the signal generator to produce an arbitrary waveform.

The arbitrary waveform generator uses direct digital synthesis (DDS). It maintains a

phase accumulator of

phaseAccum ulatorSize

bits (see parameter table below) that

indicates the present location in the waveform. The top bufferAddressWidth bits of the

counter 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.

bufferAddressWidth

phaseAccumulatorSize

arbitraryWaveform[0]

arbitraryWaveform[arbitraryWaveformSize-1]

…

Phase Accumulator

The generator steps through the waveform by adding a deltaPhase between 1 and

phaseAccumulatorSize

-1 to the phase accumulator every clock period (dacPeriod). If the

deltaPhase is constant, the generator produces a waveform at a constant frequency

that can be calculated as follows:

outputFrequency=

dacFrequency

arbitraryWaveformSize

deltaPhase

(phaseAccumulatorSize-bufferAddressWidth)

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 specified intervals.

Parameter

Value

Original/A/B models

Value

C/D models

phaseAccumulatorSize

32 bits

bufferAddressWidth

14 bits

16 bits

dacFrequency

200 MHz

dacPeriod (= 1/dacFrequency)

5 ns