can't output a right answer from divide function in sbRIO

[jwan887]

Hi,

I'm using sbRIO 9636 to generate a sine wave with an amplitude of 1V. The divide function in my FPGA VI seems have some problem.

For example, if I divide 1 with 1, the answer is 1 when I chose integer output type. But when I chose single floating point output type, the answer is 1.07E9. I found this is 2^32, but don't know why and how to fix it.

Thanks,

Jiaqi

[jwan887]

I think the problem may due to the floating point calculation in FPGA.

If I do need floating point calculation in FPGA, can I add a time delay in the loop to guarantee that there's enough time to do this?

[Matt_L]

Hi jwan887,

I haven't seen the same behavior myself on the FPGA, when simply testing all single floats and a divide function inside a while loop, with no other processing in the background on a similar sbRIO.

You shouldn't need to change the loop timing, as single floats aren't usable in single-cycle timed loops, and in a regular while loop the code should throw a compile error if the timing isn't met.

Could you post a screenshot of the relevant section of your code?  I'd like to see what else is going on that could cause this issue.

[tannerite]

It may also be useful to list the versions of your software you notice this in.