nrf calendar

RE: nrf calendar

Simonr — Thu, 12 Nov 2020 06:37:29 GMT

Torbjørn seems to have answered you in this thread.

Best regards,

Simon

RE: nrf calendar

manikandan — Tue, 10 Nov 2020 19:01:16 GMT

omg i learned so much about rtc from you guys thanks and sorry for keep bugging you i grasped everything about that nrf calender except one thing why are you using this function and what is the purpose of this function

void nrf_cal_set_callback(void (*callback)(void), uint32_t interval)
{
// Set the calendar callback, and set the callback interval in seconds
cal_event_callback = callback;
m_rtc_increment = interval;
m_time += CAL_RTC->COUNTER / 8;
CAL_RTC->TASKS_CLEAR = 1;
CAL_RTC->CC[0] = interval * 8;
},

and also count=CAL_RTC->COUNTER /32.768; how can i print these

and also what happens when overflow occurs and how can i rectify that

REGARDS

MANIKANDAN V

RE: nrf calendar

Simonr — Tue, 10 Nov 2020 08:06:20 GMT

Not by using the RTC peripheral, no. The most power efficient solution, I think would be to find a second low power MCU that is dedicated to tracking time at millisecond accuracy. If you insist on only using the nRF52, you will have to use the TIMER peripheral in order to achieve millisecond accuracy.

Best regards,

Simon

UPDATE: I'm sorry, I was mistaken regarding the RTC. If you change the prescaler to 0 in the calendar example the RTC will run at the full 32.768kHz clock speed, and if you divide the RTC counter value by 32.768 you should get the current time in milliseconds.

The important factor is that you need to update all references to the CAL_RTC->COUNTER register, since this value will now be much higher (rather than increase by 8 every second it will increase by 32768 every second).

Also, the maximum time the RTC can run without being cleared will be much shorter, since the 24-bit RTC counter will overflow in 512 seconds when the prescaler is 0.

RE: nrf calendar

manikandan — Mon, 09 Nov 2020 12:02:35 GMT

power consumption is important to me is any any alternate way to get milli seconds

RE: nrf calendar

Simonr — Mon, 09 Nov 2020 09:24:58 GMT

Hi again

The return_time = m_time + CAL_RTC->COUNTER / 8; function stores the current timestamp in seconds. If you want to edit this to store in milliseconds instead, you will have to use the TIMER peripheral instead, as the RTC is not accurate enough to count milliseconds.

Best regards,

Simon

RE: nrf calendar

manikandan — Sat, 07 Nov 2020 05:38:59 GMT

can u please explain what does this function does return_time = m_time + CAL_RTC->COUNTER / 8;

RE: nrf calendar

Simonr — Wed, 04 Nov 2020 06:55:21 GMT

Yes, you will have to implement the millisecond parameter yourself in the nRF calendar example, as it is not a part of the calendar example by default. Please check out these previous DevZone tickets that clarify some general points on the calendar example, and answers some questions on the example itself.

Best regards,

Simon

RE: nrf calendar

manikandan — Tue, 03 Nov 2020 11:10:10 GMT

in nrf_cal_get_time_string() hery are using this function strftime(cal_string,80,"%F-%H:%M;%S",nrf_cal_get_time()); to get the time and date but i dont know how are calculating date and time. and also there is no command to get millisecond in timer.h too

RE: nrf calendar

Simonr — Tue, 03 Nov 2020 10:19:37 GMT

I don't see why that should be a problem, but you'll have to implement that into the project, as it is not there by default. You can start out by checking out the while (true) loop in the main() function of the nrf_calendar example. There you can see how seconds and minutes are set, and you can implement milliseconds in a similar fashion. You will also have to edit the nrf_cal_get_time_string() function in nrf_calendar.c to use milliseconds as well.

Best regards,

Simon