FPGA selection criteria

[Wan81]

Hi,

I am thinking of purchasing an FPGA in order to synchronize multiple components together. The reason why FPGA is chosen is because I believe with an onboard processor, my whole system does not have to rely on PC processor clock or processing speed to trigger the components I have. In other words, it can work as a standalone system.

However, for labview based FPGAs, what should my selection criteria be. I have read that basically there are 3 different types of FPGA hardware targets: Compact RIO, NI R series intelligent DAQ and NI compact vision. However, I'm kinda overloaded by the info provided.

Can someone help me by providing a selection criteria I should base my judgement on when getting an FPGA?

Thanks

[Captain_Kirby]

Hi Wan81,

We do have quite a few choices when it comes to FPGA. If you just want to more accurately synchronize your data acquisition, you might just look into an R series card. These have an FPGA, but still rely on windows to host them. You can create a VI that runs on the fpga that will provide syncronised samples from the different analog and digital IO on the card, and then return these samples to your windows host VI for processing. In this way, you dont garuntee that your processing is deterministic, but you do garuntee that all your IO is syncronized. You could also use an R series card for controlling an output based upon inputs. Assuming the control is simple enough to fit onthe FPGA, you could aquire data with the FPGA, process it, and then provide an output all with in the card, and not interface with your windows system except to start and stop the VI, or to simply monitor the inputs an outputs.

If your control is more complex then can fit in the largest 3 million gate R series card, then you may concider compactRIO, which includes a real time system in conjunction with the FPGA. This allows you to offload part or all of your controll to the real time system. The real time VI will be deterministic in its timing, but will not be as precices as the FPGA. If you just want to syncronize data aquazition across all the analog and digital I/0, then this may be overkill for you since in the end, you will probably just transport your samples from the FPGA, through the real time VI, and into a host machine connected VIA ethernet.

The final option that may make sense, is one of our new Single Board RIOs (they were just released this week.) They provide all the functionality of the cRIO, but without the ruggedization. It includes a processor running a real time operating system, an FPGA (of various sizes,) and it also includes analog and digital I/O on some models (versus buying C series Modules in addition to the cRIO.) But again, this is basically a cRIO, built into a single PCB, and so it may still be overkill for your application.

The real question you need to ask is "What type of control, if any, do I need to implement with my data?" If the answer is "none", then you should probably just stay with an R series card. If you need to do complex control and processing with the data, then a cRIO or a single board RIO may be the solution.

[Bassett_Hound]

Wan81,

I would first decide what form factor you want.  Our R-series devices fit into our PXI or PCI form factor that can be integrated with other NI Products such as RF Boards, Modular instruments, and our DAQ products.  The PXI controller we offer can be both Windows based or a Deterministic Real-Time OS varaiety of varying speeds.  The PXI and PCI systems will be bigger, but will have many options for additional high performance devices.  If your planning on using the system in a more rugged environment where temperature and shock and vibration is a concern, than the current CompactRIO Platform may be the way you would want to investigate. The CompactRIO platform offers deterministic Real-Time along with a varied set of IO modules to meet the needs for industrial applications where space and environmental conditions are a concern.  

So the easiest thing to answer first is what environment are you going to put the device, how much space do you have, and do you have the need to integrate in Modular instruments such as DMMs, RF Boards, etc...

Basset Hound