FPGA Global Variable Creation

[johnoc]

According to https://decibel.ni.com/content/docs/DOC-19962 it is possible to create a global variable in an FPGA. 

To do this in the host or in the RT portion of a project it is quite straight forward. For the FPGA area in a project, not so.

Am I missing something? Do I need to create the GV  file in the Host or RT section and then move the file under the FPGA section? 

I am working in LV 2014.

Please Help!

[Hooovahh]

Sorry I don't have FPGA installed at the moment, is it not on the palette under structures?

[Dragis]

A Global is just another type of VI. Once you've created it, you can drop it into your FPGA application and use it just like you would on other targets like the Desktop. As far as the file goes, It can be located under any target in the project, or not in the project at all. If it's used in a target and not explicitly under that target it will show up in the dependencies for that target.

Note, global variables are "global" within a target. Therefore, you cannot use a global to transfer data between targets such as between an FPGA and the Desktop, or between two FPGAs. 

[crossrulz]

Its rare that you will need a global variable in FPGA.  Typically this is done with a register or memory.  But if you really want to use the global, I recommend just making it in another target and drag it to your FPGA section.

[GerdW · Accepted solution]

Hi John,

I cannot see the problem here!

I open a VI in/on the FPGA target and change to its BD, then I open the functions palette and grab a "global variable" from the structures palette.

Ready: I got a new global variable in the FPGA target…

[Dragis]

One thing I just noticed is the FPGA project "New" menu is missing the "New ..." option that allows you to create a Global. Perhaps that is where the confusion comes from. Like mentioned earlier, dropping a new Global from the Structures palette or using Quick Drop will hopefully be reasonable workarounds.

[johnoc]

Thanks all!

I just had a brain fart.

I right clicked on my target in the project and then 'New'. Variable was not an Item as it is in the RT and Host portion of the project.

It actually dawned on me after I sumitted the post.