Peer to peer nfc possible? Field strength available?

RE: Peer to peer nfc possible? Field strength available?

endnode — Wed, 13 Feb 2019 20:54:04 GMT

Well NFC (as well as BT classic and LE) are always peer to peer communication protocols. So if you have on the other side reader (aka ISO14443 PCD role) which can drive the 13.56MHz field then you will have P2P communication. Just the roles will stay, nRF52 (in both 832 and 840 variant) can only emulate card (PICC) never a reader side. If you really insist on what NFC forum calls "peer-to-peer" mode where both sides are changing the roles periodically then no, you cannot use Nordic chips as they are designed today.

The biggest question would be who the hell would like to use NFC P2P protocol (which is basically dead) in 2019?! The biggest proponent was Google with Android NFC API in very early stage but they discovered pretty soon that reader and card emulation modes are the way forward. Why you simply don't use this architecture (so you would do bi-directional data exchange by something like push/pull APDU protocol on application layer)?

As you say if you have other MCU then nRF52 on the "other" side then it can be NFC controller (chip with front-end) from NXP or ST or anyone else and it will work. Basically all examples in low-power deeply embedded microcontroller space are based on this reader/card emulation topology, just look on STM32 dev kits (e.g. nucleo boards) or Arduino compatible NFC boards...

RE: Peer to peer nfc possible? Field strength available?

tamez — Wed, 13 Feb 2019 20:12:44 GMT

endnode hello. Just wondering if anything has changed since over 1 year ago. You mention that we "need some additional HW on top of at least one board" to have peer-to-peer capabilities. So, if we have the nRF52832 or nRF52840 on one side, and a more powerful, active, NFC device on the other side, is it possible to send AND receive data on the nRF52 ?

RE: Peer to peer nfc possible? Field strength available?

HurleyResearch — Thu, 12 Oct 2017 23:25:39 GMT

indeed, your answer plus some more reading, and it all makes perfect sense, thanks.

RE: Peer to peer nfc possible? Field strength available?

endnode — Thu, 12 Oct 2017 21:49:05 GMT

Oh yes. All that is related to internal Tx/Rx representation which is running on top of EasyDMA and NFCT registry. But when you read how actual communication is done on HW level it's just modulation while listening to the field. This i how "tags" (or better PICC = contactless "cards") work to receive data and send something back. But if you read somewhere how NFC peer-to-peer mode works you need to have field driving capability on both sides. So this is kind of no-go, to talk nRF52<=>nRF52 over NFC means that you need some additional HW on top of at least one board.

RE: Peer to peer nfc possible? Field strength available?

HurleyResearch — Thu, 12 Oct 2017 21:28:27 GMT

huh... thanks for the quick responses btw. I'm reading in the nRF52840 product spec, on page 475...

"41.1 Overview The NFCT peripheral contains a 13.56 MHz AM receiver and a 13.56 MHz load modulator with 106 kbps data rate as defined by the NFC Forum."

And there's all sorts of talk about transmitting, not just receiving. Are we talking about the same chip or am I missing something else?

RE: Peer to peer nfc possible? Field strength available?

endnode — Thu, 12 Oct 2017 21:22:54 GMT

In any question related to NFC reader capabilities you can read that chip has no means how to generate 13.56MHz field so it can be only PICC (tag) never PCD. As consequence it can be neither reader nor part of peer-to-peer communication.

Actually I put NFC phrase into the search box and these are relevant Q&S just from the first page of results on this forum:

RE: Peer to peer nfc possible? Field strength available?

HurleyResearch — Thu, 12 Oct 2017 21:12:49 GMT

naturally I searched, but didn't find anything... can you suggest a search phrase that would get me a better answer?

RE: Peer to peer nfc possible? Field strength available?

endnode — Thu, 12 Oct 2017 20:54:22 GMT

Nooooooo (search the forum before you ask).