CC1314R10: Setting RTC with custom value. - No driver code found in SDK only reset is provided.

Hello, 

From another E2E they recommended something like this, although I would recommend not modifying the RTC if you are actively using the radio or using the BLE stack as they both depend on specific timings from the RTC and could cause issues if modified. 

__STATIC_INLINE void hal_rtc_sec_set_2(unsigned int sec)
{
    AONRTCDisable();
    uint32_t diff = HWREG(AON_RTC_BASE + AON_RTC_O_CH0CMP) - HWREG(AON_RTC_BASE + AON_RTC_O_TIME);
    HWREG(AON_RTC_BASE + AON_RTC_O_SEC) = sec;
    HWREG(AON_RTC_BASE + AON_RTC_O_CH0CMP) = diff + (uint32_t)((sec&0xFFFF)<<16);
    AONRTCEnable();
}

Thanks,
Alex F

Hi Alex,

Thanks for replying back.

I will first clearly explain my product use case.

We are kind of building wireless sensor and gateway model. In which multiple sensors will be connected to one gateway, and all the sensors will normally be in sleep, and when their reporting time comes, they will wake up from sleep and transmit data to the gateway. Gateway will be an active network manager, and it will be continuously listening. So Gateway will be having the network time, and all the sensors should use this same time.
When a sensor is joining or rejoining a network, the gateway will transmit the network time (simply its RTC time), and the joining sensor should configure this value to its RTC.

So I need to set sensor's RTC whenever its joining the network (in worst case scenario I may resync my network time ).


Now From your response,

Alex Fager said:

I would recommend not modifying the RTC if you are actively using the radio or using the BLE stack as they both depend on specific timings from the RTC and could cause issues if modified. 

In my use case I will be using the Radio as well. So can you kindly help me to achieve my requirement? (Can I turn off the radio and update the RTC and turn it on?)

Also I am having some doubts on the code you are sharing,

My Init , write and read APIs are as follows,

void rtc_init(void)
{
// Make sure RTC is off before config
AONRTCDisable();
AONRTCReset();
SysCtrlAonSync(); // wait for reset done

// Enable RTC module
AONRTCEnable();
SysCtrlAonSync(); // ensure enable applied
}

void rtc_set_time(uint32_t new_sec, uint32_t new_subsec)
{
// Stop RTC
AONRTCDisable();
SysCtrlAonSync();

// Write directly to RTC registers
HWREG(AON_RTC_BASE + AON_RTC_O_SEC) = new_sec;
HWREG(AON_RTC_BASE + AON_RTC_O_SUBSEC) = new_subsec;
 SysCtrlAonSync();

// Start RTC again
AONRTCEnable();
SysCtrlAonSync(); //ensure RTC start takes effect
}

uint32_t rtc_read_ms(void)
{
uint32_t sec = AONRTCSecGet();
uint32_t subsec = AONRTCFractionGet();

// Convert 32-bit subsecond to milliseconds
uint32_t msec = (uint32_t)(((uint64_t)subsec * 1000ULL) >> 32);

return (sec * 1000 + msec);
}

But In your shared code you are taking diff between the current time and channel 0 compare value, why is it so?

__STATIC_INLINE void hal_rtc_sec_set_2(unsigned int sec)
{
AONRTCDisable();
uint32_t diff = HWREG(AON_RTC_BASE + AON_RTC_O_CH0CMP) - HWREG(AON_RTC_BASE + AON_RTC_O_TIME);
HWREG(AON_RTC_BASE + AON_RTC_O_SEC) = sec;
HWREG(AON_RTC_BASE + AON_RTC_O_CH0CMP) = diff + (uint32_t)((sec&0xFFFF)<<16);
AONRTCEnable();
}


***As I already asked in my question

Muniyappan R M said:

Also From manual I understand there is no need for channel config if we are using RTC for timing alone. channels are needed to enable when we are using events, 

So Do I need to enable channel 0 as well?


Sorry for asking too many questions, Kindly help me to understand this RTC functionality.
Thanks in Advance.

Regards,
Muniyappan R.M

Hello Muniyappan R.M

Muniyappan R M said:

In my use case I will be using the Radio as well. So can you kindly help me to achieve my requirement? (Can I turn off the radio and update the RTC and turn it on?)

I would recommend turning off the radio (and making sure all the commands finished), then updating the RTC before starting the radio again. 

The code I posed was taken from another E2E, there is one of my older responses about RTC:

There are a few ways to manipulate the RTC, one I would recommend is use the functions defined by the driver library found here. The driver library resource provides many functions that can be helpful when manipulating the RTC. 

There are also a few other threads on E2E which discuss the use of RTC:

RTC TIME RESET ON WATCHDOG RESET - Bluetooth forum - Bluetooth®︎ - TI E2E support forums

CC2642R-Q1: cc2642 RTC peripheral - Bluetooth forum - Bluetooth®︎ - TI E2E support forums

Rather than manipulating the RTC of the device itself I would recommend using a global variable you set the calculates the "offset" or delta of the current time of your parent device's RTC vs the child device's RTC, then using AONRTCSecGet() to figure out that delta and store that locally to use in your application.

Thanks,
Alex F

Hi Alex,

Thanks for replying back.

I will do this one. 

Alex Fager said:

I would recommend turning off the radio (and making sure all the commands finished), then updating the RTC before starting the radio again. 

I referred to the below and it is the same as the link that I have shared (both don't have the RTC set APIs).

Alex Fager said:

There are a few ways to manipulate the RTC, one I would recommend is use the functions defined by the driver library found here. The driver library resource provides many functions that can be helpful when manipulating the RTC

Also, thanks for your recommendation on using the offset. But we may prefer reconfiguring the RTC of sensor device to the gateway's current network time so that It will be useful when implementing frequency hopping based on the current network time.
So I have implemented the rtc_set_time() API as I shared and It is working. 

As an extension to my question,If you have some time,  Can you kindly help me on implementing the Sleep and Wakeup using RTC event?.

Till now I have configured the events on RTC channels; now I want to implement standby mode and set the wake up source as RTC event and wakeup.

I think there is no example on standby mode in the SDK, I found some E2E threads,
CCS/CC1310: How to set up standby mode and wake up from RTC? 

 RTOS/CC1310: Standby and wake-up by RTC 

But I think none of them are configuring the RTC events. So can you kindly help me to achieve standby mode and wake up using RTC events?


Thanks and Regards,
Muniyappan R M.

Hello Muniyappan R M.

I do want to ask if you are using TI-RTOS here, reason being is that messing with the RTC will also affect TI-RTOS events. 

Next on the RTC wakeup it should be possible but there are other ways to do it as well, see the following thread that discusses RTC:

(+) RTOS/CC1310: CC1310 : How to wakeup from Standby by timer（RTC）every 8ms - Sub-1 GHz forum - Sub-1 GHz - TI E2E support forums

Most of the time I recommend customers to use the clock driver to generate the period for sleep and schedule the wakeup. 

Thanks,
Alex F

Hi Alex,

Thanks for the response. 
 

Alex Fager said:

I do want to ask if you are using TI-RTOS here, reason being is that messing with the RTC will also affect TI-RTOS events. 

We are using FreeRTOS, not the TI-RTOS. So is it safe to manipulate RTC? . (I hope FreeRTOS timer is not based on the RTC timer.)

Alex Fager said:

Most of the time I recommend customers to use the clock driver to generate the period for sleep and schedule the wakeup. 

In my case, the sleep period can go high, like 1 hour, 4 hours or even 12 hours (depends on the user).

So using the clock driver, can I achieve that? (using FreeRTOS as well)


Regards,
Muniyappan R M.

Hello Muniyappan R M.

Per the TRM we should be able to use the GPT (general purpose timer) or SysTick. For the purpose of this long sleep question I will look into GPT here. 

The GPT can be configured as up to 32-bit one-shot/periodic timer, which if my math is correct is around 18 hours of time we can store in it (assuming its counting at a rate of 32 kHz).

CC13x4, CC26x4 SimpleLink Wireless MCU Technical Reference Manual

So you should be able to use the GPT to create a long sleep period of 1-4-12 hours.

Thanks,
Alex F