Introduction

This guide explains the RFID/NFC module features and functions. T

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The standard

RFID (Radio Frequency Identification) is a technology that uses electromagnetic fields to identify objects in a contactless way; it is also called proximity identification. There are 2 elements in RFID communications: the RFID module (or reader/writer device) and an RFID card (or tag). The RFID module acts as the master and the card acts as the slave; this means the module queries the card and sends instructions to it. In a normal RFID communication, the RFID module is fixed and the user takes his card near it when he needs to start the interaction.

An RFID card can be understood as a remote storage unit where we can read and write information without contact. Most of the RFID tags are passive, which implies that the RFID module must create an electromagnetic field in order to power the tag. The RFID card's antenna (in fact it is an inductive coupler) gets the power from this field. Also, an RFID card has a very basic micro-controller which manages the communications and memory access.

Many RFID standards have been released by the industry. Most of them have as operating frequency 13.56 MHz or 125 kHz. In the present document we will be explaining the RFID/NFC module, which works at 13.56 MHz.

In particular, Libelium has created an ISO/IEC 14443-A and NFC compliant module for Waspmote. The ISO/IEC 14443-A protocol is widely accepted as the de facto RFID at 13.56 MHz standard. Billions of ISO/IEC14443-A cards have been sold over the world. NFC (Near Field Communication) is an extension of RFID which focuses on communications between smartphones and other advanced devices. NFC is a set of standards based on previous RFID protocols like ISO/IEC 14443-A.

There are basically 3 ways to interact with an RFID card; Libelium's RFID/NFC module allows the developer to implement the 3 of them:

the RFID/NFC module reads the RFID card's unique identification (UID)
the RFID/NFC module reads the RFID card's internal memory (16 bytes each time)
the RFID/NFC module writes in the RFID card's internal memory (16 bytes each time)

Among the RFID/NFC applications, the most common are: