Near Field Communications (NFC) is a short-range, wireless connectivity technology designed to be intuitive. NFC enables simplified transactions, data exchange, pairing, wireless connections, and convenience between two objects when in close proximity to one another. Because the communication is one-to-one and requires such close proximity, data privacy is more inherent than with other wireless approaches.
NFC has three communication modes: Read/Write, Peer-to-Peer, and Card Emulation.
Read/Write Mode
In Read/Write mode, an NFC reader/writer (or NFC-enabled mobile phone acting as a traditional contactless reader/writer) reads data from NFC-enabled smart objects and acts upon that information. With an NFC-enabled phone, for example, users can automatically connect to websites via a retrieved URL, send short message service (SMS) texts without typing, obtain coupons, etc., all with only a touch of their device to the object. Most embedded applications that utilize Near Field Communications will use Read/Write mode for the link.
Read/Write Mode for Embedded Systems
In embedded application cases, an NFC-enabled device, such as a mobile device, will provide the active reader, and the tag will be in the embedded system.
Key Points
For embedded applications, an NFC tag functions like a dual port memory: one of the memory ports is accessed wirelessly through an NFC interface; the other port is accessed by the embedded system via an I2C interface.
RF interface does NOT require power to the tag: because NFC connected tags are passive, they can be read from, or written to, by the external source even when the embedded system is powered off.
NFC connected tags function facilitate any application that requires data transfer between the embedded system and an external system with an NFC reader/writer, such as an NFC-enabled mobile device.
While the special features of connected tags offer more flexibility and benefits than standard NFC tags, the RF interface is still a passive operation (only responds to receipt of RF energy from a reader antenna source). Thus, unlike reader chips, NFC connected tags do not require emissions compliance certification with its associated extra development time, added complexity, and additional cost.
Peer-to-Peer Mode
In Peer-to-Peer mode, any NFC-enabled reader/writer can communicate to another NFC
reader/writer to exchange data with the same advantages of safety, security, intuitiveness, and
simplicity inherent in Read/Write mode. In Peer-to-Peer mode, one of the reader/writers behaves as a tag, creating a communication link. For example, two devices (such as smartphones) with readers/writers can communicate with each other.
