Challenge: Clocking a waveform in reverse

[Timmar]

Hi All,

I have an application that simulates a moving vehicle. 

This vehicle has a number of characteristics that are represented by waveforms.

As the vehicle speed increases, the waveform compresses accordingly.

The waveforms are incremented in milimeters, so each dt represents 1mm

I use a counter timer to clock the waveform. By changing the Frequency I can change the speed of the vehicle (1 hz = 1 mm/second).

This method becomes problematic when you want to go in reverse.

At the moment, I have a mirror image of the waveform that I have to offset and re-load

Does anyone know of a clever way to get an m-series (6229 et al) to reverse clock a waveform with out fliping and re-loading?

[Florian.Ludwig]

Hi Timmar,

it's really hard for me to guess what you are trying to ask.

The description of what you are doing doesn't really tell me what that is. Maybe some pictures would help - the vi would be even better.

Your question seems to be how to "go in reverse". Maybe it's because I didn't understand your introduction, but I have no idea what that means.

Similarly I don't know what "reverse clock a waveform means". A waveform is just an Y-array, t0 and dt (and attributes) - if you'd like it reversed you'll have to reverse the Y-array.

Why is m-series hardware involved in a simulation?

I hope the above helps you to rephrase your question in a way that gets you answers from this forum.

Regards

Florian

[Ben]

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@Timmar wrote:

Hi All,

...This method becomes problematic when you want to go in reverse.

At the moment, I have a mirror image of the waveform that I have to offset and re-load

Does anyone know of a clever way to get an m-series (6229 et al) to reverse clock a waveform with out fliping and re-loading?

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I know of no method clever or not.

That use case is so rare that I would be suprised to find any hardware that could do that.

Ben

[Timmar]

I guess I am thinking too Low Level,

There are a number of CMOS Counters (74xx/40xxx) that have an Up/Down Clock Functionality.

Other applications:

Image Processing - First person shooters games - Look Left, look Right,

Displays with scrolling dot matrix Text.

I used to work with Seiko 20col,2row character LCD's that would have an 80 character memory and you would clock up/down to display different sections of text in RAM..

The applications exist,

I was wondering if the HW designers at NI had considered the possibility.

I could save my application a bunch of processing if it did.