CC1352R: Reading RTC Timer Ticks

Brett Preston

Part Number: CC1352R

Dear TI,

I have a time stamp application, but would like to use the 32Khz clock (SCLK_LF) as the clock source for the ticks since it will still be running in standby mode. Can I change the clock source of the time stamp module from the system clock to the SCLK_LF? I expect the RTC is being clocked by the SCLK_LF, but don't see an easy way to read the RTC ticks? I see I can create a clock from the ClockModule, but those all seem to use the system clock as their source as does the time stamp module.

Thanks,

Brett

over 3 years ago

0 Marie H over 3 years ago

TI__Guru* 81911 points

Hi Brett,

I would recommend letting the CC1352R control the clock source itself.

Are you using an RTOS in your application?

Cheers,

Marie H

+1 Brett Preston over 3 years ago in reply to Marie H

Prodigy 50 points

Yes, we will be using TIRTOS and we do plan on letting the RTOS control the power saving modes. Regardless, I want to time stamp a falling edge of a signal that could fall when the 1352 is in standby mode. The edge should wake the processor up. I see how to generate an interrupt when a GPIO sees an edge. In the ISR I want to read the RTC value. I should be able to use AONRTCCurrentCompareValueGet () right? I'm working in the cloud and the compiler says

gpiointerrupt.c", line 45: fatal error #1965: cannot open source file "driverlib/aon_rtc.h"?

I'm wondering, for a TIRTOS application, can I use the capture feature of the RTC to capture the value on a falling edge of a signal. Just curious how much of the RTC I can use. There is a warning about not reconfiguring it because the RTOS uses it.

Thanks!

Brett

0 Siri over 3 years ago in reply to Brett Preston

TI__Guru* 86241 points

Hi Brett

I do not think it is a problem to read the RTC, but you should be careful and not re-configure it since it is used by TI-RTOS.

I took the rfWakeOnRadio example, where a packet is transmitted everytime a button is pushed, and read the rtc in the GPIO interrupt callback. That seemed to work just fine.

Modification to the original code is shown below:

#include DeviceFamily_constructPath(driverlib/aon_rtc.h)

.
.
.
.
.
static uint32_t ISRTime;

/***** Function definitions *****/
/* GPIO interrupt Callback function for CONFIG_GPIO_BTN1. */
void buttonCallbackFunction(uint_least8_t index) {

    /* Simple debounce logic, only toggle if the button is still pushed (low) */
    CPUdelay((uint32_t)((48000000/3)*0.050f));
    if (!GPIO_read(index)) {
        /* Post TX semaphore to TX task */

        ISRTime = AONRTCCurrentCompareValueGet();

        sem_post(&txSemaphore);
    }
}

Siri

0 Brett Preston over 3 years ago in reply to Siri

Prodigy 50 points

Wow, ok, thank you so much! Sorry I didn't get back to you sooner.

Sub-1 GHz

Sub-1 GHz forum

CC1352R: Reading RTC Timer Ticks