Hi! I'm currently using Arduino nano 33 ble board which contains NRF52840 in it. I'm wondering if there is a way to wake up the whole system from the SYSTEM OFF mode? My desired plan is to let the system enter the deepest sleep mode (system off mode) for 5 minutes, and then wake up on it own to read measurements from a sensor and transmit the data via BLE. After these tasks are done, it goes back to system off mode again for 5 mins.
Since the whole project requires a extreme low power consumption, I may not want any external peripherial (like an external timer RTC) to be connected to the Nano board and draw more current from it.
From the datasheet, I know NRF52840 has a built-in internal RTC and timer provided by HFCLK controller and LFCLK controller if I didn't misinterpreted the datasheet. I also found that the LFCLK controller is turned off under system off mode so it is not possible to use it. So I would like to know if there is any way to reach my plan with HFCLK or there is any other methods to accomplish my goal? Thank you.
