NFC is an acronym for Near Field Communication. NFC is a somewhat recent ‘labeling’ for a subset of RFID (Radio Frequency Identification) for short-range, wireless protocols. While NFC type RFID can apply to low frequency (LF), high frequency (HF), and ultra-high frequency (UHF) types, it’s most commonly associated with HF and used for close-range applications (hence the “near field”). NFC has some features that distinguish it from other forms of RFID, such as the capacity for bidirectional peer-to-peer communication. This article, An Introduction to NFC, is part of a series of articles intending to serve as a complete and practical guide to NFC.
The NFC Forum Standard
The most widely adhered-to standard for Near Field Communication technology is maintained by an entity known as the NFC Forum. NFC devices use inductively coupled coils to generate an electromagnetic field that is used to transfer data over short ranges (typically, between 1-10 centimeters) within the universally-recognized radio frequency band of 13.56 MHz at speeds of 106 to 424 Kb/s
| Range | 1-20 centimeters (depends on the tag characteristics and the reader used) |
|---|---|
| Frequency | 13.56 MHz |
| Speed | 106, 212, or 424 Kb/s |
| Communication Modes | P2P, Reader/Writer, and Card Emulation |
| Modes of Operations | Active and Passive |
| Tag Types | Tag 1 Type, Tag 2 Type, Tag 3 Type, Tag 4 Type, and Tag 5 Type |
Communication Modes
NFC currently utilizes several signaling technologies, or modes of operation, including Peer-to-Peer mode, Reader/Writer mode, and Card Emulation mode. Each of these modes of operation specifies how an NFC device involved in a transaction of data will behave — as an interrogator/initiator(active), target (passive), or both.
Peer-to-Peer Mode — In Peer-to-Peer mode—or P2P for short—both NFC devices switch between active and passive roles to exchange information bidirectionally. Each device is active (acting as the interrogator/initiator) while sending information/data and passive (serving as the target) while receiving information/data. This mode of operation is slower than the two alternatives due to its need for a “heavier” protocol to manage the two-way communication in a manner that avoids data collision (i.e., so that both devices know which role to take at what time).
Reader/Writer Mode — Reader/Writer mode involves one-way communication between an active device (e.g., an NFC reader or a smartphone in reader/writer mode) and a passive device (e.g., an NFC tag/inlay). The NFC device in Reader/Writer mode (active) acts as the interrogator by powering the passive NFC device by generating a magnetic field. The passive device (again, typically a tag or inlay) responds with its stored information by using the magnetic field from the reader.
Card Emulation Mode — Card Emulation mode is used in applications such as contactless smart cards and NFC-enabled credit cards to make one-tap transactions. In this mode of operation, an NFC device can behave as if it were a contactless smart card.
| Peer-to-Peer Mode | Reader/Writer Mode | Card Emulation Mode | |
|---|---|---|---|
| ISO | 14443 | 14443, 15693 | 18092, 21481 |
| Use Case Examples | Sharing information, Bluetooth pairing | Access control, Business cards, Marketing, Transactions, Asset tracking | Contact-less transactions, Access Control |
Modes of Operation
Active — In active mode, both NFC devices send and receive data actively by generating an RF (radio frequency) field. This mode of operation requires that both devices have a method of actively powering itself—devices such as a smartphone or an active (self-powered/battery-powered) tag.
Passive — In passive mode, one NFC device, the initiator, generates an RF field and the other NFC device, the target, uses the first device’s RF field to send its stored data back to the first device via a process called load modulation. This is the most common mode of operation of near field communication because passive tags (which are less expensive and lack a battery) can be used.
Tag Types
| Tag 1 Type | Tag 2 Type | Tag 3 Type | Tag 4 Type` | Tag 5 Type | MiFare Classic | |
|---|---|---|---|---|---|---|
| Standard | ISO-14443A | ISO-14443A | Japanese Industrial Standard (JIS) X 6319-4 | ISO-14443A | ISO-15693 | ISO-14443A |
| Read/Write Capabilities | Read/Write capable (can be configured as read-only) | Read/Write capable (can be configured as read-only) | Read/Write or Read-Only | Read/Write or Read-Only | Read/Write or Read-Only | Read/Write or Read-Only |
| Memory | 96 bytes – 2 Kb | 96 bytes – 2 Kb | < 1 Mb | < 32 Kb | < 1 Mb | 192, 768, or 3584 Bytes |
| Data Speed | 106 Kb/s | 106 Kb/s | 212 or 424 Kb/s | 106, 212, or 424 Kb/s | 106 Kb/s | 106 Kb/s |
| Anti-Collision | None | Supports Data Collision Prevention | Supports Data Collision Prevention | Supports Data Collision Prevention | Supports Data Collision Prevention | Supports Data Collision Prevention |
| Technology | NFC-A | NFC-A | NFC-F | NFC-A or NFC-B | NFC-V | |
| Example Tag/s | Innovision Topaz, Broadcom BCM20203 | NXP MIFARE Ultralight | FeliCa | NXP DESFire, SmartMX-JCOP | NXP MIFARE Classic 1k, MIFARE Classic 4K, and Classic Mini | |
| Use Case Examples | Business cards, Bluetooth pairing, One-time provisioning, Read-only applications | Event passes, Transit passes, URL redirects, Transactions | Transit passes, eMoney, Transactions, Electronic ID, Membership cards, Home automation | Electronic ID, Transactions, eMoney, Identity validation, Access control | Product identification, Library books, Asset tracking |
For more information concerning tag types, refer to www.nxp.com and the NFC Forum.