Host/FPGA/CLIP Synchronization

[major4x]

I have been developing some continuous acquisition from RIO hardware and I have spent at least a week being stuck, so I finally I decided to help. Things almost work but not reliably. I am attaching my design. What doesn't work is the following:

1. The user selects some channels (Boolean controls);

2. The user starts hosts.vi;

3. After initialization the Boolean control "Start" is triggered;

4. After start is triggered, the CLIP in the design asserts the "Started" signal and a number of "Enabled" signals;

5. After "Started" is received a number of FIFOs start loop-reading.

My problem is that sometimes this works, but in most cases I never get the "Started" signal back from the CLIP. Either I timeout, or I get Started but I don't get any Enabled signals, despite they are asserted in the same clock-cycle as the Started signal (by the CLIP).

Thanks a lot for your ideas!

[shawn.t]

Have you tried wrapping all the front panel controls and their connections to the I/O lines (on the right side of the third sequence frame) within a timed loop that runs off the I/O clock?  Without surrounding that logic with a loop, it'll only run once.  That may be why sometimes you're able to start sampling, and sometimes you're not.  It depends on how fast the host machine sets those controls (i.e. they must be set before that third sequence frame is executed).  Also, if the 'started' line depends on the 'start' line, then you should should never see it engage because that would be at least one clock cycle after the logic is complete.

[a.feldman]

Thanks for the suggestion. I will try it on Monday and will write here what happens. I thought it maybe like what you said if the I/O's are latched at boot and I was planning to investigate the auto-generated VHDL but the latter is not exactly readable ... Thanks again for this suggestion!

[Intaris]

So are Major4x and a.feldman the same person?  You know you can re-use your profile so that people can keep track of your progress instead of thinking every post is from a new person...

[a.feldman]

Yes, sorry about that. I have accumulated a number of accounts during the years. I will mail NI to delete the redundant ones.

[a.feldman]

@shawn.t: Yes, this works, thanks! Pretty amazing that you can spot these things without debugging!

[shawn.t]

I do what I can... 

Glad it worked out!