Low Power with RTC and RAM retention

[Pietro Beraldini]

Hi, I'm working with nRF52832/nRF52840 and SDK 15 or 15.2 on Windows with Segger Embedded Studio.

Is it possible to use the device in low power mode, but keeping active one instance of RTC and with RAM retention (without using Softdevice)?
Can someone explain or link some examples or suggestions of how implement it?

Thank you very much!

[Jørgen Holmefjord]

Hi,

RTC can only be run in System ON mode. In System OFF mode, all clock sources are stopped and only RESET/GPIO/NFC/LPCOMP can wakeup the chip. In system on mode, the RAM is always retained. You enter system on mode by calling __WFE() (when no softdevice is enabled).

Best regards,
Jørgen

[Jørgen Holmefjord]

All examples in our SDK enter system on sleep mode when there is no CPU activity going on. You will see this current if you remove all inits from an example and call __WFE() in main loop. Remember to reset the board after flashing to make sure it is not running in debug mode.