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CC26xx: using RTC under TIRTOS

Slava Ermachkov
Prodigy 210 points
Other Parts Discussed in Thread: CC2640

Hi,

I tried to read from CC2640's RTC in the same way as it done in rtc driver and other functions that I found:

key = Hwi_disable();
curSeconds = HWREG(AON_RTC_BASE + AON_RTC_O_SEC);
curSubseconds = HWREG(AON_RTC_BASE + AON_RTC_O_SUBSEC);
Hwi_restore(key);

It works, but curSeconds value is 0 after each reboot.

I want to implement a 4-byted UNIX-time watch in CC26xx TIRTOS-based app (e.g. SimpleBLEPeripheral). Don't need to use any TimeApp GATT services. Just need to place 4-byted UNIX time to hardware RTC and get it back in a hour or day. Reading topics such as e2e.ti.com/support/wireless_connectivity/f/538/p/413259/1470336  leadis me to conclusion that it's impossible to use CC26xx's RTC as RTC itself in TIRTOS.

In previous practice I widely used embedded RTCs (or external RTCs such as DSxxx) for UNIX-time or real time counting and don't understand why I cannot use it in MC that contains RTC and 32KHz crystal.

How should this task (reboot-independent UNIX-time watch) be solved in CC26xx application with TIRTOS?

  • 0
    TI__Mastermind 29650 points
    Hi Slava,

    The RTC should not be accessed directly in TI RTOS unless you know what you're doing since the value is latched between reads of seconds and subsecond. The Clock_getTicks() API should be used to access the RTC indirectly instead.

    We do unfortunately not have an RTC whose value are retained during a reset so it will read 0 every time you reset.

    Regards,
    Svend