What is NFC?

NFC or Near Field Communications is a short-range wireless connectivity technology that allows two compatible devices to communicate without contact. This two-way wireless communication technology uses radio waves operating at a base frequency of 13.56 MHz. This technology provides wireless communication between a pair of NFC-enabled devices (reader & tag) at a distance of less than 10 cm.

NFC delivers data speeds of 106 Kb/s, 212 Kb/s, 424 Kb/s, or 848 Kb/s which is enough to move small pieces of information almost instantaneously. NFC is very similar to RFID however the biggest difference between the two technologies is that RFID provides one-way communication while NFC provides two-way wireless communication.

NFC-enabled devices have inbuilt NFC chips which consists of RF circuits, amplifier, clock, microcontroller, and some memory to send/receive the data. Of the two NFC-enabled devices, at least one of them should be active (i.e., externally powered) and the other device can be either active or passive. Example of active NFC device include smartphones, security pads, tablets, or payment terminals while smart cards are passive NFC devices.

An active NFC device can work in three modes: peer-to-peer, read/write mode, and card emulation.

• Peer-to-peer mode (P2P): In this mode, two NFC-enabled active devices (for example, two smartphones) directly share files and information. While one smartphone sends data, the other one act as receiving device.  In this mode, both the devices generate the radio wave alternatively at a carrier frequency of 13.56 MHz.
• Read/write mode: In this mode, an NFC-enabled active device reads data from an NFC-enabled passive device (tag) or writes data on the tag by generating the radio wave alternatively at a carrier frequency of 13.56 MHz.
• Card emulation mode: In this mode, the NFC-enabled active device acts as a passive device to communicate with the receiver terminal. The active device does not generate any radio waves, but it responds to the receiver terminal for requested data transfer.

Applications of NFC:

NFC allows one-way or two-way wireless communications and is used in many applications such as paying bills, passports & ID cards, exchanging business cards, downloading coupons, or sharing a research paper, social networking for sharing photos/videos/files, gaming, and sports applications.

How does NFC work?

Reader-mode

NFC works based upon the electromagnetic induction (transformer principle). The NFC chip of the transmitter generates AC voltage at a frequency of 13.56 MHz and drives the transmitter coil (antenna). This AC voltage leads to a current flow through the coil that creates an alternating/rotating magnetic field. The magnetic field induces an emf in the receiver coil to rectify it and power up the NFC chip inside the tag.

NFC Standards   

The NFC (Near Field Communication) Forum is a group of non-profit industry associations established in 2004, including electronics products manufacturers and original equipment manufacturers (OEMs). The forum promotes the use of NFC in consumer electronics products, PCs, mobile devices, and IoT devices. They develop and promote NFC standards for both wireless power transfer and digital data transfer to ensure interoperability & better service between NFC-enabled electronic devices.

The NFC standards, such as FeliCa, ISO14443 Type A, ISO14443 Type B, and ISO 15693, describe the communications protocols and data exchange formats.