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The main difference between RFID and NFC when emulating an NFC tag on ACR122U

I have some problems with the overview of the NFC standards.

What i know is that:

  • ISO/IEC 14443 is the standard for proximity cards and use RFID as communication protocol;
  • ISO/IEC 18092 (NFCIP-1) is the NFC standard and is based on ISO/IEC 14443;
  • NFC Forum has build on top of ISO/IEC 18092 a standard which include the NFC Forum type tags (ISO/IEC 18092 tags) and LLCP;
  • The ACR122U is a reader which can read inter alia ISO/IEC18092 and ISO/IEC 14443;
  • The ACR122U emulates a NFC Forum Type 4 Tag on top of ISO-DEP (ISO/IEC 7816-4) on top of ISO/IEC 14443-A;

I have two questions:

RFID or NFC tag

What i don't understand is why the emulated tag is a NFC tag. If the emulated tag is based on ISO/IEC 14443-A it is a proximity card and as far i understand the technology of a proximity card is RFID. So why is this a NFC tag and not a RFID tag? What is the technical difference?

Where comes the RFID and NFC part during communication

NFC is compatible with RFID (13.56 MHz). I gues when a tag get scanned by the ACR122U it will determine if it is an RFID or NFC tag. This probably would be done by identifing some flags and/or an initialization procedure. If it is an NFC tag it will use the ISO/IEC 18092 standard to communicate, if it is a RFID tag, it will use ISO/IEC 14443.

But if the emulated tag is an NFC tag build on top of ISO/IEC 14443 it is a NFC tag (ISO/IEC 18092), but it needs to be controlled according to the ISO/IEC 14443 standard. During initalization and communication, what is the RFID part (ISO/IEC 14443) and what is the NFC part (ISO/IEC 18092)?

I don't know if i'm right but this is confusing me.

Any related information is welcome.

Thanks.

Solution

  • What I don't understand is why the emulated tag is a NFC tag. Why is this a NFC tag and not a RFID tag? What is the technical difference?

    There is none. Call it NFC tag or RFID tag, or even better proximity contactless smartcard. That's just how terminology evolved. Today, pretty much anything that can be read with an NFC device is called "NFC tag" while everything else is called "RFID tag", but there's no clear separation.

    There is also the term NFC Forum tag, which refers to NFC tags that comply to NFC Forum Tag Operation specifications. For instance, this would be the case if you implement the Type 4 Tag platform on top of ISO/IEC 14443-4 (ISO-DEP).

    I guess when a tag get scanned by the ACR122U it will determine if it is an RFID or NFC tag.

    See above, there is no technical difference. As the ACR122U contains an NFC controller, every tag/smartcard that you can read with it will fit both "NFC tag" and "RFID tag".

    If it is an NFC tag it will use the ISO/IEC 18092 standard to communicate, if it is a RFID tag, it will use ISO/IEC 14443.

    No, ISO/IEC 18092 ony specifies peer-to-peer mode functionality that is compatible to ISO/IEC 14443 and JIS X 6319-4 (FeliCa protocol). So if it's a tag, the NFC controller will speak the protocol defined in ISO/IEC 14443 or JIS X 6319-4 (or NFC-A/B/F from Digital Protocol) with the tag. If the reader/NFC controller talks to a passive peer-to-peer mode device or a tag is determined through protocol parameters/flags during the anti-collision and initialization phase. E.g. for type A as a flag (= bit) in the SAK (select acknowledge) byte that -- if set -- tells the reader side that the counterpart supports NFCIP-1 (ISO/IEC 18092).