Event groups

valeriv wrote on Thursday, July 28, 2016:

Hi all
I use Event Groups to synchronize starting of the tasks.
For example run the FIRST TASK and in the specific moment use
uxSetBits = xEventGroupSetBits( *mEventBits, BIT_0 ) - to set the bit.

and other tasks is BLOCKED on
uxWaitBits = xEventGroupWaitBits( *mEventBits, BIT_0, pdFALSE, pdFALSE, 50000 );

And everything is working correctly, but if I debug the situation I see that
uxSetBits sometimes is 1, and sometimes is 0.
uxWaitBits ALWAYS is 1 and all the tasks exits the blocked state when bit set (not on timeout).

I am really worried about the fact that xEventGroupSetBits not set bit.
What do you think about this ?

p.s. I have no tasks with higher priority than FIRST TASK, the only task with the same priority is TmrSvc

Thanks in advance


rtel wrote on Thursday, July 28, 2016:

I’m afraid I don’t fully understand your question, and without being
able to see the rest of the code it would be difficult to provide an
answer anyway.

I assume your intention is for the code to execute in such a way (the
order in which the tasks run, etc.) that the event group value would
always be 0 when xEventGroupSetBits() was called - but that is evidently
not the case. If so, perhaps the trace tool could help you visualise
how the application is being scheduled so you could adjust as necessary.

That said, if the system is actually executing as you expect, and you
only see this anomaly when debugging, perhaps it is the interaction with
the debugger that is actually causing the anomaly.

valeriv wrote on Thursday, July 28, 2016:

Which trace tool do you have in mind ?
Thank you very much.

rtel wrote on Friday, July 29, 2016:


valeriv wrote on Sunday, July 31, 2016:

thank you