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mohamad_armoon
mohamad_armoon
Associate III
September 19, 2014
Question

need to have time separate from main loop_stm32f407

Posted on September 19, 2014 at 15:30

hi every body 

in my program i need to do somethings in specific time , this ''time'' is not equal all the time.

for example for doing first job i need to do it 5 sec after a flag become set. and after that i need to make it zero and after that doing second  job when this timer is more than 3sec

this timer has not stop ever . it has to count separately from the any other part of cpu.

and it should be as much accurate as counting milisecond.

note in this case i cant use Systick because i using it for something else.

thanks in advance 
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    4 replies

    Tesla DeLorean
    Tesla DeLorean
    Guru
    September 19, 2014
    Posted on September 19, 2014 at 17:09

    And why can't you use an RTOS, or schedule it with the SysTick, or another timer? All the clocks here are synchronous, and clocking at sub-microsecond granularity.

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    mohamad_armoon
    mohamad_armoonAuthor
    Associate III
    September 19, 2014
    Posted on September 19, 2014 at 18:41

    i know it would be ok if i use RTOS , but i don't know any thing about RTOS, and somehow i fear of ROTS because the lack of knowledge. i don't know how should i compile my code beside RTOS .

    as much as i go deep on my code i feeling  lack of threads. if it was in computer i just used threads , semaphore and ..... i know that these problems has solved by RTOS. but i don't know about them
    Andrew Neil
    Andrew Neil
    Super User
    September 19, 2014
    Posted on September 19, 2014 at 21:40

    ''i don't know any thing about RTOS''

    Time to start learning, then...?!

    Or just do it on a timer - as clive1 also suggested...
    A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
    Andrew Neil
    Andrew Neil
    Super User
    September 19, 2014
    Posted on September 19, 2014 at 21:44

    ''i cant use Systick because i using it for something else''

    But one of the key applications of SysTick is as the timebase for the entire system - so perhaps you have a poor design if this one use of SysTick precludes all else?

    Anyhow, other timers are also available...
    A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
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