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TI Home » TI E2E Community » Support Forums » Development Tools » TI C/C++ Compiler » TI C/C++ Compiler - Forum » __delay_cycles() does not work correctly with while/for loops
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__delay_cycles() does not work correctly with while/for loops

__delay_cycles() does not work correctly with while/for loops

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tech
Posted by tech
on Apr 15 2012 09:57 AM
Prodigy120 points

Hi you all!

I  have tried to write a simple delay function (CCSv4.2 for MSP430) like:

void Delay_ms(unsigned short usMilliseconds) {

   while ( usMilliseconds-- )     {

        __delay_cycles(32768);
    }

}

I didnt inspect the resulting assembly code but it does not work (release/debug) . After second loop "usMilliseconds" is reset but the delay will be still executed (it stays there indefinitely).

Is this a known problem?

Thank you

Tech.

MSP430 CCS4.0 _delay_cycles()
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  • AartiG
    Posted by AartiG
    on Apr 16 2012 09:26 AM
    Guru69005 points

    Did you disable the watchdog timer prior to this code being run? It sounds like the watchdog is resetting the device, which happens after every 32768 cycles for MSP430 devices.


    If a post answers your question please mark it with the "Verify Answer" button

    Search the wikis for common questions: CGT, BIOS,  CCSv3, CCSv4
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  • Archaeologist
    Posted by Archaeologist
    on Apr 16 2012 10:04 AM
    Mastermind40800 points

    Also note that you should probably be using a low power mode rather than __delay_cycles for delays of that magnitude.  See http://processors.wiki.ti.com/index.php/Compiler/diagnostic_messages/MSP430/1527

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  • tech
    Posted by tech
    on Apr 28 2012 05:28 AM
    Prodigy120 points

    Yes, of course I have disabled the WDT. It seems to be a bug pls. see my answer below. Thanks!

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  • tech
    Posted by tech
    on Apr 28 2012 05:29 AM
    Verified Answer
    Verified by tech
    Prodigy120 points

    Yes I disabled it. It seems to be a bug in CCS see Post "CCS 5.1.1.00031 "Step Over" doesn't work for MSP430 __delay_cycles intrinsic"

    I have tested it again but with CCS Version: 5.2.0.00044  and it seems to work properly!

    Thank you very much.

    Tech.


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  • Martin Gomez
    Posted by Martin Gomez
    on Jun 18 2012 16:49 PM
    Prodigy10 points


    hi.. i have a question, if i use a external cristal of 8MHz, and i divide it in 8 for give 1MHz, how works the funcion "__delay_cycles();"?, what cycles use of based? in the internal cycles or in the external cristal?

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  • George Mock
    Posted by George Mock
    on Jun 19 2012 14:37 PM
    Guru51445 points

    The __delay_cycles intrinsic consumes the given number of CPU cycles.  Cycles lost to system effects such as memory wait states are not considered.

    Thanks and regards,

    -George


    TI C/C++ Compiler Forum Moderator
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