RFID, NFC & UWB · Study deck

NFC Protocols: Handover Boundaries

An NFC tap only works when the reader and the tag agree on a mode and then hand over cleanly to the protocol that carries the data.

Radio Remi is your guide for this deck.

modesprotocols
Radio Remi, the module guide, in a scene from this chapter.
iotclass.org

After studying this chapter

Learning objectives

You will be able to:

  • Explain: While tracing release evidence, keep both: Compatibility and: Policy outcome visible in it.: Release only when failures are classified by boundary: identifies the later check.
  • Explain: NFC failures often appear as "the tap did not work." Good release evidence makes those failures diagnosable before field rollout.
  • Explain: Bluetooth, Wi-Fi, and Thread commissioning often use NFC as a setup input rather than as the long-running connection.
  • Explain: The label path needs reader/writer tests with the actual tag family, record size, lock state, and mounting surface.
iotclass.org

Major section

Handover Boundary

Handover is a boundary pattern, not a promise that NFC will carry the whole session.

  • NFC carries enough information to identify the peer, select a carrier, or pass a setup token.
  • The application owns: Authorization, device binding, user confirmation, telemetry, retry rules, and rollback when setup fails.
NFC handover boundary between tap setup and follow-on connection
NFC handover boundary between tap setup and follow-on connection
iotclass.org

Major section

Initiator, Target, and Passive Communication

Having a battery does not mean the phone owns the field.

  • Every NFC exchange has an initiator that starts and drives the exchange and a target that responds.
  • This distinction explains several field failures.
  • A successful "phone seen by reader" test can still hide a credential-policy failure.

Why it matters

A phone can read an unpowered sticker because the phone is the initiator generating the field and the passive tag load-modulates a reply.

iotclass.org

Major section

Technology Matrix and Compatibility Evidence

The label path needs reader/writer tests with the actual tag family, record size, lock state, and mounting surface.

  • Beneath the modes are RF technologies inherited from HF RFID smart cards.
  • A tap works only when both sides share a supported technology.
  • The cabinet path needs card-emulation tests against the installed readers and accepted application identifiers.
iotclass.org

Major section

Release Evidence

NFC failures often appear as "the tap did not work." Good release evidence makes those failures diagnosable before field rollout.

  • While tracing release evidence, keep both: Compatibility and: Policy outcome visible in it.: Release only when failures are classified by boundary: identifies the later check.
Release evidence for NFC modes and protocol reviews
Release evidence for NFC modes and protocol reviews
iotclass.org

Major section

Concept Relationships

NFC Security and Comparisons: Threat models and controls depend on the operating mode and trust boundary.

  • Bluetooth, Wi-Fi, and Thread commissioning often use NFC as a setup input rather than as the long-running connection.
  • NDEF records should be schema-checked before they drive IoT actions.
  • Tag type choice should be documented with compatibility and release evidence, not only with memory size.
iotclass.org

Deck summary

Key takeaways

Handover is a boundary pattern, not a promise that NFC will carry the whole session.

  • Having a battery does not mean the phone owns the field.
  • The label path needs reader/writer tests with the actual tag family, record size, lock state, and mounting surface.
  • NFC failures often appear as "the tap did not work." Good release evidence makes those failures diagnosable before field rollout.
  • NFC Security and Comparisons: Threat models and controls depend on the operating mode and trust boundary.
iotclass.org

Retrieval practice

Recall check 1 of 2

Radio Remi says: answer from memory, then check your reasoning.

Q1A phone taps a payment terminal to pay. Which NFC role and communication behavior is the phone using?

AReader/writer mode, with the phone generating the RF field to actively read the terminal.
BPeer-to-peer mode, because two active devices are involved in completing the tap.
CCard-emulation target mode; the terminal field powers the exchange.
DActive mode, because the phone has its own battery so it must power the field.
Show answer

Answer: C NFC payment uses card emulation with the terminal as initiator powering the field and the phone as target replying by load modulation.

iotclass.org

Retrieval practice

Recall check 2 of 2

Radio Remi says: answer from memory, then check your reasoning.

Q2A maintenance tablet taps an NFC label on a pump. The label contains an NDEF URI with the pump identifier, and the tablet then opens the work-order app. Which design statement is strongest?

AThe NFC label proves the pump identity, so the app can immediately unlock maintenance actions.
BThe tap selects an object; the app must validate payload and policy.
CNDEF handles the security decision because it standardizes the record format.
DThe tablet is using card emulation mode because it is near an industrial asset.
Show answer

Answer: B Reader/writer mode is useful for deliberate object selection, but the NDEF payload crosses a trust boundary.

iotclass.org

Print reference

Answers

Answer key.

  1. C · NFC payment uses card emulation with the terminal as initiator powering the field and the phone as target replying by load modulation.
  2. B · Reader/writer mode is useful for deliberate object selection, but the NDEF payload crosses a trust boundary.
iotclass.org