Logic Analyzer: repeated run not working

[asdfex]

Hi,

since some time I can't set the logic analyzer using a Digital Discovery to automatically keep running. Behavior is the same in 3.20.1 and the latest 3.20.28.

As expected, a click on "Single" causes the LA to trigger once and return to "stop" mode.  But using "Run" causes exactly the same behavior, although after a trigger it should go back to 'armed' mode. I can't find which wrong setting might cause this problem. Any ideas?

 

Edited August 29, 2023 by asdfex

[attila]

Hi @asdfex

When capturing a lot of samples and the transfer time takes more than one second the repeated mode is stopped. This prevents the application from becoming unresponsive. For long captures and traditional logic analyzer behavior the Record mode should be used.

[JColvin]

Hi @asdfex,

Could you share a screenshot of your workspace so I can see your settings?

If you are on the default Trigger settings (Trigger type set to Normal, Source set to Digital, and the Simple option, instead of Pulse or Protocol, selected) the Logic Analyzer will run indefinitely because whatever signals you have added will by default have an "X" underneath the T column (trigger condition), indicating that this pin state will be ignored by the trigger bus.

You'll want to change the pin state to something else by clicking on the X to change the condition to high or falling or edge, or whichever state you prefer so that there is a condition to meet on one of the pins. You can set multiple of these pins to different conditions to create a more complex scenario where only very specific set of conditions causes the Logic Analyzer to be triggered.

Alternatively, you can choose Pulse instead of Simple to get a time based trigger (such as a glitch condition, timeout, or a counter) on a singular pin.

Some additional information about this is available in the Help tab in the Logic Analyzer section (sections 2 and 2.1 within Logic Analyzer), which is quickly accessible by pressing F1 while on the Logic Analyzer instrument.
You can also have it jump to a specific section in the Help tab by clicking/interacting with a specific element within the UI (such as the Trigger mode dropdown of None, Auto, and Normal) and then pressing F1, though not every UI element supports this.

Let me know if you have any questions.

Thanks,
JColvin

[asdfex]

@JColvin Thanks for the extensive answer, but @attila hit the point:  It's a bit unexpected, but indeed the transfer time was rather long. If I change from 4Mi to 2Mi samples or reduce the number of inputs from 32 to 16, the repeated mode works again.

I'm looking for events happening seldomly, so the data transfer time doesn't matter in this case. Maybe one can replace the full stop by a short sleep between end of transmission and going to armed mode again? Then there should be enough time for the application to respond to user action, but it also eventually returns to data taking.

 

Thank you!