A software interrupt ends on its own when viewing on trace...any explanation?

[cpeng]

Hi Devzone:

We are using J-link pro to collect trace data from nRF52833 DK board, and we found a rather strange behavior:

The sw interrupts would end on its own without PE coming back from the call stack to end it.

See ozone screenshot below:

a little explanation of the doodle in the picture: "another main() fills in" is a ozone display artifact. Guess it doesn't know how to handle a interrupt ending pre-maturely so it inserts a second main.

So regarding the problem, shouldn't the sw interrupt (the orange bar) continue extending to the right till PE comes back from the call stack? Why does it terminate pre-maturely?

Thanks.

[haakonsh]

That's probably a bug in Ozone. I suggest you ask Segger for help as well.

If it's not a bug in the debugger tool then it indicates a stack corruption which should cause the system to behave erratically, do you observe such symptoms, other than the "extra" main thread?

Are you running any RTOS, SoftDevice, or similar, or are you just running the ESB library? 

[cpeng]

Hi no the code runs fine on nRF52833. We don't use any RTOS or SoftDevice, we do use ESB library.

So it's most likely a display bug in Ozone. Thanks for helping.

[jmr]

Hej cpeng, have you found a solution to this?

I'm facing a similar issue but with softDevice enabled. I found that Ozone provides a User Action called OS.AddContextSwitchSymbol() which AFAICS can be used to make Ozon aware of a context switch. However, until now Ozone seems to be unhappy with it as it stalls and I have to kill the application.

[cpeng]

Hi jmr:

Unfortunately I haven't found the root cause of the problem, my intuition tells me that ozone doesn't really know how to handle hardware interrupts.

[jmr]

Hej cpeng, 
I have been successful using the OS.AddContextSwitchSymbol(). 
You can experiment with it easily by calling the function in the Ozone Console at the very beginning of your debugging session (e.g. halt at main)
If you are comfortable with the results, you may want to add the calls to your .jdebug file. 

Happy debugging! :-)

[cpeng]

Thanks for the tip jmr! I will give it a try if i have a chance.