Hello,
I need to force an OS context switch immediately after some IRQ is handled (power failure detection) - I cannot allow any other task to run after the IRQ except the highest priority task that is waiting for a signal. But I cannot allow the task that was interrupted to finish its time slice, thus I'm trying to induce a SWI by this code
VICSoftInt = (1<<4) ; // the constant used to address the proper hardware time is placed in "RTX_cofig.c"
However, I see that the IRQ is repeatably triggered (even if the matching register is reset!), and the SWI function is never executed (at least, in a test program that is running on the simulator). This is clearly something in the architecture (ARM7) I'm not aware of, but I did not find anything in the documentation prohibiting this. Can you enlighten me...?
Doesn't it work with a normal isr_xx() call to force a task switch?
As soon as your ISR ends, the RTX will then do a timer tick interrupt, allowing it to switch to a high-prio task that doesn't give any CPU time to any other tasks.
An alternative - if this is the end of the game for you - is to use the ISR to turn off interrupts (in case you allow nested interrupts) and then do what you need to do before the power is lost.
Per,
Thanks for your reply. I will have a look at RTX's sources to see if the behavior is as you decribed (I assumed the same when I wrote the code - I am trying to find an explanation for a weird failure - but that's another story...). Maybe I missed a statement about this behavior in the RTX manual. Thanks for your reply.
It seems that this entire effort will not be necessary - RTX will indeed force a context switch using the very same method as I posted above.