Sending altered signals to an external/stand alone device

[RedAG]

Hi guys,

Is it posssible to alter a digital signal acquired from an external device and then send it back to it?

Now, I understand this is very generic and my question does not provide any specifics, but I will happily provide them, step by step, if anyone needs to know.

[Eden_S]

Hi Sugarman,

Thanks for your question. Yes it is possible, but as you said this is a very generic request so more information is certainly required.

What external device is it? How do you wish to alter the signal? Will you be using LabVIEW or any software?

Thank you,

[RedAG]

Hi Eden,

Thanks for the reply! Well, it's a generic question for 2 reasons. 1, it is a rather complicated project (atleast for me, a newbie to LabVIEW) and 2, I am finding out information and ideas as I go along.

In a nutshell, I wanted to display digital signals obtained from an external (non NI device/devices) through LabVIEW. How these external signals look like/what they mean/how many there are, I have no idea. This is the part I'm trying to figure out.

I started off trying to just display a random digital signal throgh LabVIEW. I managed to do this with a lot of help from some excellent members in these very forum. I have a PXi-7813R, whichs FPGA through which I programmed to ro capture a random signal (a 5V ). the actual physical connection was through an SCB-68 connector.

Going back to the original project, as far as I am aware, there would be about 4, 5 or 6 digital signals (which includes clock and some sort of data I am sure of) which needs to be acquired through the NI instruments I have and then alter one or more of these signals. When I mean alter, I mean altering the bitsream in one or more of these signals and then send back to the original device. The original device will have a EEPROM or a register of some sort which I want to reset with the signals I send out.

The external device is in effect a chip with an EEPROM. I want to use LabVIEW to do this.

Let me know if you require any other info and I will provide them.

[Eden_S]

Hi Sugarman,

Firstly I am very sorry that it has taken so long for a response; I have been out of the office for quite a while. Again, the information is a little bit vague to give any specific advice. 

All I can say at this point is what you propose will be perfectly possible using LabVIEW. As you have already done some programming with FPGA, this application should not be too difficult (most of the functions you describe are quite basic).

Again, I'm sorry that this information is vague. I really couldn't suggest any specifics (functions, toolkits, architecture, etc.) until you are more sure about hardware/signals. All I can say thus far is that reading a digital signal, modifying it, and writing it back to a device should be very easy.

Many thanks,

[RedAG]

Thanks Eden. 

I know my next step is to go about trying to figure out how these external signals obtained from the external device would look-like and behave. For this purpose, I would require a Logc Analyzer to analyze these external signals fed in to the FPGA. Someone in this forum mentioned that the FPGA can be programmed to act as a Logc Analyzer. Do you know how or how I should go about desiging a Logic Ananlyzer using the FPGA?

Any resposnse from anyone will be much appreciated.

Thanks 

[johnsold]

Do you know anything about the external signals, such as timing range or data rate?  Do you know what kinds of "alterations" you will need to make?

You indicated that one of the signals was a clock.  Measure the clock frequency with a counter. Then use either that clock or an internally generated clock at a higher frequency to sample all the other signals. You can display the results on a graph and you have a rudimentary logic analyzer.

Lynn

[RedAG]

Thanks Lynn,

I do no know anyhting about these external signals unfortunately. That information is hidden somewhere in the Patents! 

What do you mean by 'alterations'? Do you mean the duration of a single pattern of signal?

Also, I am a new to LabVIEW, so not so sure how I use this counter to figure out the frequency of the signal. I would think that it is a little more complicated than connecting the FPGA input to the counter!

Also, when you say "Then use either that clock or an internally generated clock at a higher frequency to sample all the other signals", do you mean using the clock signal as a reference to sample the other signals? To do this, wouldn't I need to know how many signals there would be?

Thnaks again for your help.

Anoop

[johnsold]

Anoop,

Are you trying to reverse engineer the device which generates these signals? Do you have the legal permission to do so?

Trying to analyze completely unknown signals without any information can be very difficult.  But, the purpose of a patent is to reveal the information about the invention, while providing protection to the inventor of the rights to use it.

If what you are doing is legal, then read the patent or hire someone to do it. There should be quite a bit of information in it.

Lynn

[RedAG]

Hi Lynn,

YES! reverse engineering. In a nutshell, I am trying to read the signals transmitted between a a DEVICE1 and a DEVICE2 or the communication that exists between them. I cannot however tell you what kind of devices these are as I am bound by my contract.

Once I have read this signal, I want to control the one of these Device2 using LabVIEW FPGA. There is a memory or a counter of some sort in Device2, which I want to write to. I know the type of memory there is EEPROM. Does this make sense?

What I am are trying to do is legal. The folks in the company who deals with these things assures me! The Device manufacturers obviously do not want to make any information available. The workings of the Devices are somewhere in the patents. I have searched the US patents pretty much everyday for the past 2 onths without finding anything relevant.

From what I understand, by looking at the patents of similar devices is that there would be a EEPROM, which can be written into, which would have a Clk, rst, data and some other signal/signals. 

Unforntuantely, hiring someone for this kind of purpose is rather expensive and i would think very costly.