How to keep RTC running while in system off mode?

RE: How to keep RTC running while in system off mode?

lilealyh — Thu, 09 Jul 2020 03:44:00 GMT

Hi jorgen.I genuinely appreciate your help and support.

RE: How to keep RTC running while in system off mode?

Jørgen Holmefjord — Wed, 08 Jul 2020 14:12:48 GMT

sd_app_evt_wait() will enter System ON idle mode. The CPU will wake on any generated event, i.e., if you have RTC running, the CPU will wake on the COMPAREx event.
There is an example for wakeup on GPIO in this GitHub repository.

RE: How to keep RTC running while in system off mode?

lilealyh — Wed, 08 Jul 2020 09:01:23 GMT

Hi jorgen:

Thanks for quickly replay.Now I understand the system off mode not possible to run RTC,I can wakeup from system off mode using GPIO pin sense,but i don't kown how to wake up from sleep mode.

1、Using sd_app_evt_wait() api whether can into sleep mode,if can and how to wake up from sleep mode?

2、If using external low-power RTCs and what should i do ?

RE: How to keep RTC running while in system off mode?

Jørgen Holmefjord — Wed, 08 Jul 2020 08:48:48 GMT

Hi,

It is not possible to run RTC in System OFF mode. All clock sources are turned off in System OFF mode. If you want to run the RTC, you can only go to System ON mode.

The Sleep Current with RTC running in System ON mode is 1.50 uA (with no RAM retention). If you need the low power of System OFF, there exists external low-power RTCs that can wake the chip from System OFF through a GPIO pin sense.

Best regards,
Jørgen