Zephyr RTC Alarm versus k_timer_start

[Jamal_nRF]

Dear Customer Support,

Wanted to open a case to follow up on this old one Case ID: 335484  

 nRF52840 with Zephyr RTOS: How to use RTC with struct rtc_time? 

I initially looked at the counter alarm under

https://github.com/zephyrproject-rtos/zephyr/tree/main/samples/drivers/counter/alarm/src

using rtc0 and counter_set_channel_alarm

Test environment nRF52840, but this seems to be pretty generic to any other nRF platform

I have few high level questions:

1-what would be the pros and cons of using the Zephyr counter alarm feature versus using the plain Zephyr k_timer_start with a registered callback?

2-with the counter alarm feature, there is an upper limitation on the alarm duration around 8 second, as obtained by

counter_get_top_value or counter_get_max_top_value

how to increase that maximum tick value to configure a higher duration value?

3-if we force the device into a power off state using sys_poweroff(), is there a possibility to wake up the device through an RTC callback

There is an available sample that shows how to wake up using a button press, so the idea is to replace the button by a RTC wake up

Thank you

Jamal

PS

I will have more follow up questions later...

[Jamal_nRF]

I have also tried this example on the nRF52840

https://github.com/zephyrproject-rtos/zephyr/blob/main/tests/drivers/rtc/rtc_api/src/test_time.c

using rtc0 instance

it does not work either

Please advise if I missing something

[Kazi Afroza Sultana]

Hello,

What is not working? Can you show some log?

[Jamal_nRF]

Hello,

I have using example provided in the above link

https://github.com/zephyrproject-rtos/zephyr/blob/main/tests/drivers/rtc/rtc_api/src/test_time.c

I call the rtc_get_time

   int ret = rtc_get_time(counterDev, &timeGet);

   if (ret < 0)

   {

      LOG_ERR("Cannot read date time: %d", ret);

      return ret;

   }

   LOG_INF("RTC date and time: %d-%d-%d %d:%d:%d",

           timeGet.tm_year, timeGet.tm_mon, timeGet.tm_mday,

           timeGet.tm_hour, timeGet.tm_min, timeGet.tm_sec);

right after initiating the RTC with

   struct rtc_time timeSet;

   time_t timeEpoch = 1738083814;

   gmtime_r(&timeEpoch, (struct tm *)(&timeSet));

   int ret = rtc_set_time(counterDev, &timeSet);

   if (ret < 0)

   {

      LOG_ERR("Failed to set time");

   }

the rtc device is defined

const struct device *counterDev = DEVICE_DT_GET(DT_NODE_LABEL(rtc0));

Enabled rtc0 in my .dts file as

&rtc0 {

   status = "okay";

};

To your question, the first log from rtc_get_time is

RTC date and time: -1--1--1 -1:-1:-1

subsequent calls to rtc_get_time return the same log

RTC date and time: 0-117617--1 -1:204237:536874088

Question back:

are you able to run this example on a nrRF52840 based devKit?

Also,

could you please be more thorough addressing my other questions?

Thank you

[Jamal_nRF]

any update on this ticket?

thank you

[Kazi Afroza Sultana]

''

using rtc0 instance

it does not work either'' 

I tried the sample and built worked now. Could you send me your application folder so I can check it here?

[Jamal_nRF]

I did not use the sample as is. I just integrated the piece of code highlighted above into my application running on a custom board using the nRF52840 chip.

Which hardware did you use to run the sample?

What does your log look like?

Jamal