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Original question:

RTOS/CC1352R: RTC 32bits overflow

CCS/CC1352R: Where is RTC timer overflow callback in SimpleLink SDK with TI-RTOS?

yingtao jia
Expert 1280 points
Part Number: CC1352R
Other Parts Discussed in Thread: CC2652P

Tool/software: Code Composer Studio

Hi,

I use SimpleLink SDK v4.20, CC2652P, CCS v10.1.

This is my clock config.

This clock's tick period is 10us, and it works fine on TI-RTOS.

The clock is 32bit, so when the timer counts full from 0, it takes 0xFFFFFFFF * 10us, this is about 12 hours. After the timer goes to 0xFFFFFFFF, then it goes to 0.

My application software need to know when the timer overflows to 0 from 0xFFFFFFFF, and I can not find this "overflow callback".

So my question is how to know when the timer overflows?

  • 0
    TI__Genius 14845 points

    Hi Yingtao,

    Assigning an expert to comment. 

    Thanks, 
    Elin 

  • 0
    TI__Guru 58425 points

    Hi Yingtao,

    There is no overflow callback as the Clock module itself cannot overflow. The Clock module allows you to setup a timer with at most 0xFFFFFFFF - 1 ticks and nothing more. Once it reaches the number you have given it it gives you the callback and then it stops OR restart again, depending on how you configured it. This means that if you for example set a periodic "1000 ticks" clock, it would count to 1000, invoke CB, and start again from 0, not continue on until it overflows.

    May I ask why you need this in your application?

    Best regards,

    Max

  • 0 in reply to IUsedToBeARealPerson (M-W)
    Expert 1280 points

    I use this code to test.

    // clock callback

    void myClockA(UArg arg1)
    {
        Semaphore_post(gSem);
    }

    // a code block

    {

    Clock_Params_init(&clockParams);
    clockParams.period = 0; // 0 is the default, but added for completeness
    clockParams.startFlag = TRUE;
    clockParams.arg = 'A';

    clockHandle = Clock_create(myClockA, 2000*100, &clockParams, NULL);

    Semaphore_pend(gSem, BIOS_WAIT_FOREVER);

    debug_printf("Start Test\n");

    while (1)
    {

        now_time = Clock_getTicks();

        debug_printf("now time : %u\n", now_time);

        delay_ms(1000);
    }

    }

    I create ClockA, set interval 2s. After the callback is triggered, print "Start Test", and then read the clock count every 1s.

    The result is as below:

    So, according to the result, the clock is running continuously, it won't stop.

    And I guess it will keep running until its count reaches 0xFFFFFFFF, and, when this happens, there should be something like overflows callback.

  • 0 in reply to yingtao jia
    TI__Guru 58425 points

    Hi Yingtao,

    Clock_getTicks() has nothing to do with the clock object you create as such. Clock_getTicks() returns the current RAT time scaled to the Clock modules domain, it does not return an internal "Clock timer" value. When you create "myClockA", no timer is started (unless you set the "START NOW" flag that is). When you issue "Start myClockA", the current time (using Clock_getTime()) is captured and the RTC channel is configured to match the clock objects timeout value. 

    Basically, Clock is an RTC wrapper and it uses the forever running RTC and has no internal timers. If you are looking for the RTC tick, you could use the RTC DriverLib functions (note that you can only use the "GetValue" without care as the kernel expect to own the configuration of the RTC module):

    dev.ti.com/.../group__aonrtc__api.html