Whats the best way, to got best powersaving mode, and Wake up with clock, nfc and GPIO?

[Jones_swDev]

Hello together,

I'm searching for a way to go I max low power mode possible an then wake a from one of three reasons:

1. Timer/Clock
2. NFC-Field
3. GPIO

I searched the web now for at least one week, but got confuesed by the NRF5 SDK and the NRF Connect SDK.
We are using the NRF Connect SDK in v 2.1.0. and we have an nrf52840.
If someone can provide some code snippets to help me, that would be great.

Greatings
Jones

[Vidar Berg]

Hello Jones,

Zephyr will automatically run the idle thread (see system threads and CPU Idling)  when there is no work to do, which will make the chip enter System ON mode (sleep). So the only thing you really need to worry about is configuration of the wakeup sources.

Timer/Clock

You can use the k_sleep() if you have a thread you want to wake-up periodically, see thread sleeping.

NFC-Field

You can have a look at the NFC samples to see how you can use the NFC to wake up on field detect events.

GPIO

This is demonstrated by the button sample.

Best regards,

Vidar

[Jones_swDev]

Thanks for your answer and your links! I will have a more detailed look at them.
Two more questions:
1. When I put the System to sleep with k_sleep(), will I be able to wake it up with GPIO and NFC?
2. Is System ON mode the lowest sleep mode possible? We need the lowest current consumtion possible...

Greetings
Jones

[Vidar Berg]

No problem.

1. Yes, the k_sleep() will make the thread that is being called from enter the waiting state. This will not block GPIOTE or NFC interrupts.

2. You have System OFF mode as well. Relevant samples for this mode is NFC: System OFF and the nRF5x System Off demo. 

Best regards,

Vidar