could an nRF52840 be wakened up wirelessly from a SYSTEM OFF mode?

RE: could an nRF52840 be wakened up wirelessly from a SYSTEM OFF mode?

p143 — Wed, 10 Aug 2022 01:15:55 GMT

Thanks Einar

RE: could an nRF52840 be wakened up wirelessly from a SYSTEM OFF mode?

Einar Thorsrud — Tue, 09 Aug 2022 17:11:34 GMT

Yes, with the clarification that here the nRF is the NFC tag. And the nRF can be wake up from system off by detecting a NFC field (which is made by a NFC reader device).

RE: could an nRF52840 be wakened up wirelessly from a SYSTEM OFF mode?

p143 — Tue, 09 Aug 2022 15:10:25 GMT

Hi, Einar.
If I got you right, the NFC-Tag, if it is programmed previously to do so, will wake up the tag from a System Off mode as soon as it detects the NFC-Receiver field. So, if I program the NFC Receiver to issue a System Off mode command, let us say 3 seconds after pushing a customized Receiver button, One could both wake up the nRF52840 with a quick sweep of the receiver on the tag or issue a System Off command on it, with a slow sweep.
Am I right?

Thanks

RE: could an nRF52840 be wakened up wirelessly from a SYSTEM OFF mode?

Einar Thorsrud — Tue, 09 Aug 2022 13:50:39 GMT

Hi Juan,

[quote user="p143"]1.- Could I wirelessly force a System Off mode in an nRF52840 with an NFC reader and keep it in this mode till I wake it back up with the same NFC reader?[/quote]

You can always make the nRF enter system off mode in any situation as long as there is a way to communicate with it somehow, as that is something that is done programatically. Also, there is no problem to use NFC as a wakeup source, as long as you configure that before entering system off mode (see for instance this snippet if using the nRF5 SDK or NFC: System OFF if using nRF Connect SDK). However, using NFC both to trigger system off and wakeup would probably not work, ad wakeup from system off happens when the field is detected, so the device would probably wake up again more or less immediately. If this is really what you want, then perhaps you could add a delay so that there is time to remove the nRF from the reader before it enters system off mode.

[quote user="p143"]2.- How would I implement the NFC Reader functionality?[/quote]

The nRF HW does not support reader functionality.

RE: could an nRF52840 be wakened up wirelessly from a SYSTEM OFF mode?

p143 — Tue, 09 Aug 2022 13:45:05 GMT

Hi, Einar.
Sorry. I thought it was the other way around. I shall then repeat my questions.
1.- Could I wirelessly force a System Off mode in an nRF52840 with an NFC reader and keep it in this mode till I wake it back up with the same NFC reader?
2.- How would I implement the NFC Reader functionality?
Thanks again.

Juan

RE: could an nRF52840 be wakened up wirelessly from a SYSTEM OFF mode?

Einar Thorsrud — Tue, 09 Aug 2022 07:36:26 GMT

Hi Juan,

I am not sure what you mean here? Can you elaborate?

Note that the nRF can only act as a NFC tag, not a NFC reader, so it is not capable of communicating with a tag. Moreover, another tag cannot wake up the nRF from system OFF mode as it wakes up when it detects a NFC field, which can only be generated by a nRF reader.

Einar

RE: could an nRF52840 be wakened up wirelessly from a SYSTEM OFF mode?

p143 — Mon, 08 Aug 2022 15:17:01 GMT

Thanks, Einar.
Reading the linked info you sent me, I deduce that you also could get the module in SYSTEM OFF mode using an external NFC tag. Is that right?
Thanks.

Juan

RE: could an nRF52840 be wakened up wirelessly from a SYSTEM OFF mode?

Einar Thorsrud — Mon, 08 Aug 2022 07:09:08 GMT

Hi Juan,

Yes, it is possible to use NFC as a wakeup source in system off, mode. If you are using the nRF Connect SDK you can refer to the NFC: System OFF sample. If you are using the nRF5 SDK and SoftDevice you can refer to this thread.

Einar