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lgberro
lgberro
Visitor II
March 12, 2013
Question

Discovering if inside an ISR

  • March 12, 2013
  • 1 reply
  • 627 views
Posted on March 12, 2013 at 21:14

Is there any way to discover if we are running inside any ISR (uart, systick, timers, etc.)? It would avoid dead-locks.

I thought reading IPSR would help, so if ISR_NUMBER is different from 0 (thread mode), then we would be running inside an ISR. But I couldn't find a way to read it.
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    1 reply

    Tesla DeLorean
    Tesla DeLorean
    Guru
    March 12, 2013
    Posted on March 12, 2013 at 21:51

    Couldn't you tell with consistent usage of Mutex/Semaphore type constructs?

    Looking at the processor state seems a bit hackish, you can look at bit 2 of LR when it contains a magic value to see if it was called as an IRQ, or specifically what stack is in use, as I recall. You could also look at what region SP resides in.

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