RE: Micro:Bit, nRF51822-QFAA and Low Power

endnode — Sat, 05 Aug 2017 10:58:09 GMT

Hi Jennifer,

That's all what you have on nRF5x chips. Either calling directly WFE/WFI low-level instructions to set your MCU to "wait for event/interrupt" mode (which is effectively "SLEEP" mode when chip is in power on state) or call subsequent SD function sd_app_evt_wait() which does effectively exactly the same inside Nordic stack. If you don't need any function running (meaning you don't wait for any RTC/TIMER interrupt or similar) and you expect to be woken-up by external trigger (button or power off/on) then you can use POWER OFF mode which basically turns everything off. However you cannot run any internal timer (so no periodical radio activity for BLE or similar thing possible) and wake-up is effectively reset procedure (you start-up the chip like it would be reset, but you can hold some volatile data through the POWER OFF).

Note that there exists how to optimize power consumption guide for nRF51 and you won't get any better advice on this forum. It's also the highest ranking Q&A from all 24k at this moment, I'm sure you've see it when searching...