RE: Power optimizing NRF beacon

endnode — Mon, 11 Jul 2016 16:15:47 GMT

Hi pbn4,

Yes, nRF5x chips have basically just "sleep during system on" and "system off". In normal app design chip (through SD or app code if it runs without stack) spends most of the time (for broadcaster only such as "beacon" it can be even >99%) in "wait for event" aka "sleep". However whole system continues in the code execution after very next "wake on event" with all state variables preserved. If you want to go better (basically if you want to go to <1uA range) you need to use "system off" but then wake-up (even you can do it by timer/GPIO/NFC sense/similar event) works as system reset so you need to perform whole start-up procedure including all HW peripherals' init, BLE stack (Soft Device) if used etc. So yes, going to "system off" will interrupt advertisement and you can use it only if you implement your own timer to wake-up and start advertising again (also note that standard BT Smart compliant advertisement - e.g. as implemented by Nordic SD - has little variations around adv. interval to prevent collisions in case some broadcasters get accidentally synchronized periods/phases, but that might be a detail which you can neglect at the first design).

Cheers Jan