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NFC peer to peer mode?

Jesper Hansen
Prodigy 180 points
Other Parts Discussed in Thread: RF430CL330H, TRF7970A

I am a little confused about the different operation modes available, and in particular peer-to-peer operation mode.

Is it possible to have a TRF7970A(initiator) and a rf430cl330h(target) communitaing in peer-to-peer mode? 

My use case scenario is like this: 

- TRF7970A receive data from rf430cl330h

- The MCU connected to TRF7970A evaluates the data and send back some data to rf430cl330h

- The MCU connected to rf430cl330h get the data through SPI

Is that possible using TRF7970A and rf430cl330h in p2p mode?  

If I have understood it, the communication can be either in active or passive mode. If one of the NFC devices is an passive tag device(no external power), the communication will be passive. Is that right?

  • 0
    TI__Guru*** 133215 points
    Hi Jesper,

    No, it is not possible to communicate with the RF430CL330H with peer-to-peer communication.

    The RF430CL330H is a Type 4B NFC Tag. It does not support peer-to-peer communication. The only way to communicate with it is by using an NFC Reader/Writer.

    Based on your use case, what you would need to do is read the data from the RF430CL330H using the TRF7970A as a Reader/Writer, process it, and then write new data to the tag again using the TRF7970A as a Reader/Writer. From there, the MCU connected to the RF430CL330H can access the new data that was written to the RF430CL330H through SPI.

    Depending on the size of the data packets and how frequently that exchange needs to occur, you may find that for your application peer to peer is a better solution. If that is the case, you would need to use another TRF7970A instead of the RF430CL330H.

    If that is something you need to test out, we have an application note for peer-to-peer communication that includes support for communicating between two TRF7970A's: http://www.ti.com/lit/an/sloa192/sloa192.pdf

    To answer your other question:
    If an NFC device is a passive tag device, then it is NOT a peer-to-peer device. An NFC tag is just that, a tag. It requires a Reader/Writer to provide an RF field along with the correct protocol for reading the tag based on the tag type (for RF430CL330H, Type 4B). The passive tag will then communicate back to the Reader/Writer by load modulating the provided RF field to send data.


    Regarding peer-to-peer in general (not the RF430CL330H), which is what you were trying to refer to:

    Active vs passive communication: For active communication, both the target and the initiator provide their own RF field to communicate with each other by turning their fields on and off to send data. For passive communication, the RF field is provided by the initiator only and remains on throughout the communication, and the target will load modulate that RF field to send data back to the initiator. Also, this does not imply that the passive device is operating without external power.

    So, in terms of peer to peer, you are correct that if an NFC device operating in peer to peer is in passive mode, only another passive device can communicate with it. An active device will not be able to communicate with a passive device even if it has a proper initiator/target relationship.


    I hope these answers will clear up your confusion. Please feel free to ask further questions if anything is unclear.