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Blinking LED using Interrupts in assembly language

Anirudh Sharma
Prodigy 30 points

Here is the code which works only if I enter into a Low Power Mode however it is not working in active mode.

Please suggest.

  • 0
    Guru 58965 points

    The job you gave the CPU is very easy, it can do it even when you let it to go to sleep (and wake up occasionally by the doorbell to flip the light). However, if you left CPU in active mode and do not instruct it what to do next, it will run away beyond your control. By that time, it won't even answer the doorbell.

    Your label Mainloop suggests a solution, but it is not really a loop . Replace that section of code by:

             bis.w   #GIE,SR      ; enable interrupts
    Mainloop jmp     Mainloop     ; stay here, don’t go away

  • 0
    Guru 227245 points

    Your Main'loop' is no loop. So if you don't enter LPM, which effectively ends main code execution, the code will continue form main into the ISR and then perform a RETI where the ISR was never called due to interrupt.

    You should add a 'jmp $' or similar after the nop, so the code execution stops there.

  • 0 in reply to Jens-Michael Gross
    Guru 12050 points
    As you removed cpuoff from the normally:
    bis.w #CPUOFF+GIE,SR ; CPU off, enable interrupts

    Then of course ProgramCounter (PC) will still run and execute any code/garbage below.

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