LabVIEW FPGA Idea Exchange

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64 bit FPGA tick-counter

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FPGA module for 64-bit LabVIEW

With availability of fast FlexRIO cards (such as NI 5761) and FPGA framegrabbers (NI 1483, PXIe-1435, NI PCIe-1433 ) data rates of 1GB/s are becoming commonplace. However, the FPGA Module is limited to communication only with 32-bit LabVIEW. Since, typically you want to store more than 2 seconds of data in RAM,you would like to use 64-bit LabVIEW as your host application. Unfortunately, this isn't possible yet.

While, I can imagine that a full blown 64-bit FPGA Module add on would be pretty difficult to build (and especially test), I believe there is a solid middle ground at this point. I can imagine, coding and compiling the FPGA in the normal 32-bit LabVIEW environment, and then just using a 64-bit host application to Read/Write front panel controls and to read/write the DMA buffers from the FPGA. I don't know the details, but this communication protocols could be very low hanging fruit if it's just a simple matter of recompiling a few key pieces for 64-bit operation.

Since the data rates passing to and from FPGAs will continue to climb, as well as the prevalence of 64-bit OS, a 64-bit version of FPGA Module is needed in the new feature pipeline. This should also be kept in mind as other new FPGA Module features and tools are created, as planning for 64-bit compatability now will make the eventual transition to 64-bit much, much easier down the road.

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I love using enums because they can often make discrete options much clearer. Example:

enum clarity.PNG

But, at least as of 2017, the below code is going to use fewer resources and propagate faster because LabVIEW is going to use an 8 bit register above instead of the two bits below.

My solution is to allow smaller integer representations of enums (I'd use a U2 in the above case).

Ideally the user wouldn't even have to specify the integer size, it could just calculate the minimum at edit time and show the user what it is.

I have several FPGA projects that require significant compile time (up to 1.5 hours), and for that I am thankful to have my compile server running on a separate computer.

The issue comes with the seven Pre-Compile steps that occurs before LabVIEW sends to the code to the compiler. On one particular project this action alone can take up to 35 minutes during which time I can do nothing on that machine.

I would like to see much of this precompile time moved from the development environment to the compile server. There already exists a mechanism for updating the user with the compile status so those precompile errors could be annunciated in a similar fashion.

Get the development system back online as quickly as possible.

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DSP48E2 Implementation

Writeable inputs to FPGA I/O nodes can be left disconnected without any warning (or broken VI indication) from the VI in which the I/O node is used. This can cause some vigorous head-scratching if the missing connection is not immediately obvious as in the screen shot below. For obvious reasons, FPGA controls have no connector assignment or "Recommended, Required, Optional" attribute. In that case, and to avoid playing "Where's Waldo" on the block diagram, I suggest making FPGA I/O node input connections implictly "required", and if not, the VI would be broken. This would be the same behaviour as seen with cluster nodes.

More RAM, bigger FPGAs

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For debugging, using FPGA VIs in interactive mode can be very valuable. I have, to this day, not been able to find out how LV determines if a bitfile and a VI match.

Therefore whenever I click on the run button for a VI, I'm never quite sure if the bitfile will match or not and often have to wait 1-5 minutes before I can resume working with LabVIEW. This is a very high price to pay for something which I end up cancelling. I would like very much if the IDE would TELL ME that the bitfile and VI don't match before starting a new compilation and thus wasting my time.

This is opposed to a CTRL_Click of the run arrow which explicitly tells the IDE to compile.

Show the price of sbRIO on the NI website

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Single-Cycle Timed For Loop

When writing LabVIEW code for an FPGA target, the most important considerations are speed and resource usage. By using the single-cycle timed loop (SCTL), we can increase the speed of the program by allowing more than one operation to complete per clock cycle. We also decrease resource usage by removing the flip-flops that would be required to store values between clock cycles for the operations in the SCTL.

However, there are limitations of the SCTL. For some operations, it takes significantly less resources to implement something using a for loop rather than a single-cycle timed loop. With a for loop, one can auto-index a result at the border of the for loop (if the preallocation of arrays option is selected) to obtain a fixed-size array (valid on the FPGA). Below is the simplest possible example:

The equivalent with a single-cycle timed loop would be:

The replace array/subset VI consumes resources proportional to the size of the array. Depending on the operation being performed, this can increase resource usage such that it is more practical to use a for loop (as shown above).

I propose the creation of a single-cycle timed for loop. Here is a very rough mock-up (MS Paint is not the most adequate of image processing tools... you will get the idea):

This solves two problems: 1) It allows for the compiler to know how many times to loop will run at compile time. It also simplifies the UI by letting the user know how many times the loop will run without having to think through a condition. 2) It allows for the more efficient creation of fixed-size arrays through a SCTL (rather than through a for loop).

Intermediate file generation in parallel

Hi, since there an be a queue for compiling FPGA code, it seems natural to me to also be able to make a queue for generating intermediate files.

I'm working with 10 build specs. for compilation per project and generating intermediate files for my design takes aprox. 3-4 minutes. This means that I need to sit by my computer for half an hour just waiting and clicking build on every build specification. Sometimes I work with FPGA VI which need to build intermediate files for something like 7-10 minutes, so this is a pain.

It would be great if there was a way of just highlighting all build specifications for compilation with shift and just creating the intermediate files for them automatically one by one.

Can this be done?

The document High Performance FPGA Devleoper's guide lists a parallelized bubble sort. I tried this out, and found that it actually doesn't work. This this matrix successfully gets the max value on top, and the minimum value on the bottom, it doesn't completely sort the values between.

Bubble Sort.JPG

In this example, if the highest value started at the end of the array (red), and the 2nd highest value started 2nd from the end (pink), the high value ends up at the top, and the 2nd highest value ends up 3rd from the top.

Bubble Sort - Markup.JPG

This lattice can be completed to sort the middle sections by adding 3 more columns, one with 3 Min/Max blocks comparing the center 6 values, one with 3 Min/Max blocks comparing the center 4, and a final Min/Max operation comparing the middle 2. This will complete the sort, but will take 7 sequential steps instead of the 4 listed. The following works to sort the entire array:

Bubble Sort - Corrected.JPG

I've searched but can't see anything similar - please add a method for setting the timeout for FPGA nodes. This includes the 'Open FPGA reference' and FPGA IO nodes.

If you disconnect a cRIO FPGA (e.g. NI 9148) from the network, it takes 20-30s for the IO node or Open FPGA reference to execute. This is really bad for the user experience as if they try to exit their application in this time it may take half a minute for the application to exit. It also means you may have to wait that length of time to realise that your FPGA has disconnected under most use cases (you can obviously have an external watchdog loop to check that the node is executing in a timely manner)

Please allow me to configure the timeouts for these nodes similar to the TCP/UDP or VISA nodes. They are very similar in how they operate to the FPGA nodes (i.e. a hardware device driver which is susceptible to disconnects!) so I don't understand why these have been omitted.

I wouldn't mind having to set the timeout as part of opening the FPGA reference and then internally have it use the same timeout for other IO nodes as follows:

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FIFO read that doesn't use 100% CPU

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The first thing you hear about programming FPGAs with LabVIEW is: use single-cycle loops. But if you build a state machine (while-loop + enum + case structure), in many cases you cannot make the outer while loop in a single cycle-loop, because not every state fits into a single-cycle loop. Therefore you have to place the single cycle-loop into every case, which has to run in one cycle, which takes up block diagramm space and is cumbersome. Therefore my idea to create a single-cycle case structure: it uses the same compiling mechanism of the single-cycle loop on every case, which is capable of running inside a single cycle. It would be nice, if this behaviour is configurable, meaning I can decide from case to case, if it is a single-cycle case or not. Some kind of right-click menu options like these: "make this case single-cycle", "make every possible case single-cycle", etc. Of course the mode of the case (single-cycle or not) should somehow be displayed.

Regards,

Marc

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Pipeline structure

My original problem was that I in the FPGA have an array of data, where I need to do some calculation, where the only appropriate way was to use a pipeline. The pipeline is a very strong tool in the FPGA, but I think the LabVIEW tools could be changed so the pipeline is easier.

My old implementation if the pipeline:

Suggested implementation of single cycle pipeline, with shift registers in the tunnels, so all the code is run on each of the 5 elements in the array.

Maybe there should be added a number of iterations (like the “for loop”), if the number of data, is not defined by the array size.

In another project I have a continuous running pipeline, I have implemented in different ways, but one simple is as shown:

Before

Here the new pipeline sequence could also be used, maybe like following:

Here it should be stated in the loop tunnel, that the input data is read continuous.

Here I have shown in both examples, that it should be single cycle times loops, but maybe the pipeline structure should also be able to run with another timing (determined by the slowest frame).

I have seen the idea about the timed frame, it will help on the last example, but there will still be need for a pipeline structure.

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LabVIEW FPGA Idea Exchange

64 bit FPGA tick-counter

FPGA module for 64-bit LabVIEW

Turbo Boost the speed of FPGA compiles under Windows (Method included!)

Allow smaller integer representations of enums

Track Device Utilization Over Multiple Compilations

Minimize Pre-Compile actions on the local computer when compiling FPGA code

DSP48E2 Implementation

"Break" VI when FPGA I/O input node is not connected

More RAM, bigger FPGAs

Interactive mode: ASK before starting a new compilation if source and bitfile don't match

Show the price of sbRIO on the NI website

Single-Cycle Timed For Loop

Intermediate file generation in parallel

Lets enqueue creating intermediate files

Math Error in Lattice Bubble Sort in High-Performance FPGA Developer's Guide 1.1

Add timeout input to FPGA nodes (Open FPGA reference, IO nodes)

FIFO read that doesn't use 100% CPU

Configurable single-cycle case structure

Drive a host timed loop with LabVIEW FPGA IRQ

Pipeline structure