Peer to peer nfc possible? Field strength available?

[HurleyResearch]

We're building small robots/toys that work with each other.

Would it be possible to use the nfct on two devices with nRF52840 to communicate between each other?

Also is there any way to get information about field strength?

Of course this is not standard usage of nfc but if possible it would be nice to have some peer to peer detection at least, then near field ranging even better, then full communications best.

Any ideas appreciated, thanks!

[endnode]

Nooooooo (search the forum before you ask).

[endnode]

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.

[tamez]

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 ? 

[endnode]

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...