LabVIEW FPGA DDS Multichannel Waveform Generator

[Evan R.]

[Edit 6/4/2009] - Replaced attachment with corrected .ZIP including the Waveform Selector.ctl - Evan Robinson

Functional Description

This example project will perform multiple channel waveform generation using DDS.

Direct digital synthesis is a technique to generate signals with very precise frequency/phase resolution. For more information on DDS please see: http://zone.ni.com/devzone/cda/tut/p/id/5516 and http://en.wikipedia.org/wiki/Direct_digital_synthesis.

Caveats and Additional Notes

Use "AS-IS"

Required Hardware / Software:

LabVIEW / LabVIEW FPGA Module

NI R-Series or cRIO based FPGA Target.

[B.Settles]

Hey Evan,

There appear to be some VI's and controls missing from the example you showed me at the Developer Day. Specifically, the ability to select the waveform type.

[Evan R.]

Hi Brandon,

Do you mind letting me know which controls are asked for specifically? I zipped the entire folder and uploaded it, so the controls much be somewhere else, I'll have to search.

-Evan

[B.Settles]

The Waveform Selector.ctl (FPGA target) is not found, and I also don't see a host example that would allow changing the waveform type.

[Evan R.]

Fixed!

Also - use the waveform selector from the host, simply use an FPGA Read/Write propery and wire to it the desired waveform. If you check out the FPGA code, you can see that the waveform selector is used as a select input choosing either sine or triangle. This could be extended for additional types of waveforms such as squares and sawtooths, etc.

Let me know if you have additional questions.

[queenlooners]

Hi there!  Not sure if you are still monitoring this feed but gonna try anyway.  For some reason, I am running into an aliasing/shifting issues.  I defined a ramp function in a lookup table as well as a pulse and for some reason my signals shift back and forth every 1.2 microseconds.  it is the oddest thing.  I figured it was due to the interpolation but i have messed with that a bit and changed my LUT from 11 bit to 14 bit for better granularity.  Still can't get away from the 1.2 microsecond shifting.  Any thoughts?

Thanks!