Overview
ISO/IEC 28361:2007 defines the Near Field Communication Wired Interface (NFC‑WI) - the digital two‑wire interface between a Transceiver and a Front‑end. The standard specifies the physical and logical behaviour of the Signal‑In and Signal‑Out wires, including electrical characteristics, state machine (Off, Activating, On, De‑Activating, Command), activation/deactivation sequences, and the bit encodings used for three supported data rates. ISO/IEC 28361 was published as an international standard to enable interoperable wired connections for NFC subsystems.
Key topics and technical requirements
- Scope: Digital wire interface between Transceiver and Front‑end; signal wires, binary signals, state diagrams, and bit encodings for three data rates.
- Clock: Reference clock f = 13.56 MHz ± 7 kHz (CLK).
- Data rates / encodings: Encodings specified for f/128 (~106 kb/s), f/64 (~212 kb/s) and f/32 (~424 kb/s). Supported coding includes Manchester and Modified Miller formats.
- States and transitions: Defined UML state model with main states - Off, Activating, On (Idle / Busy), De‑Activating, and Command. Default Command‑state bit coding is f/128.
- Activation / escape sequences: Activation and escape sequences use specific pulse counts and frequency ranges (e.g., at least 127 pulses in 2–12 MHz range on Signal‑In) and timing constraints for responses (typical response windows 100 µs to 50 ms, or up to 50 ms depending on sequence).
- Deactivation / power‑saving: Off state entered when both wires remain LOW for ≥120 µs; deactivation sequences and responses are specified to ensure orderly shutdown and power management.
- Electrical characteristics: Signalling voltage amplitude 1.62–3.63 V; input HIGH threshold ~1.10–3.63 V, input LOW threshold 0–0.70 V; rise/fall times and input/output drive limits and capacitance requirements are defined for compliance and interoperability.
Applications and who uses it
- Hardware designers of NFC front‑ends, transceivers and integrated RF modules implementing wired control and data paths.
- Device manufacturers integrating NFC subsystems in mobile phones, POS terminals, access control readers, and IoT devices.
- Test laboratories and QA teams verifying electrical, timing and protocol conformance of NFC wired interfaces.
- System integrators and firmware engineers implementing low‑level drivers and state machines that coordinate Transceiver ↔ Front‑end interactions.
Practical benefits include reliable low‑level interoperability, controlled activation/deactivation for power saving, and standardized bit encodings for data exchange.
Related standards
- NFCIP‑1 (NFC peer‑to‑peer / wireless protocol) - Annex A of ISO/IEC 28361 gives considerations for using NFC‑WI with NFCIP‑1.
- Origin: ECMA‑373 (adopted into ISO/IEC 28361:2007).
Keywords: ISO/IEC 28361:2007, NFC‑WI, Near Field Communication wired interface, Transceiver, Front‑end, signal wires, bit encoding, activation sequence, electrical characteristics.