What Is Needed for Near Field Communication
One of the reasons that NFC is so successful is that it’s a relatively simple technology (well, at least if you’re a propeller head). This figure shows the basic elements of an NFC communication in most cases. As you can see, you have an NFC-enabled device that uses a wireless connection to power and then interact with some sort of NFC information source (a card).
The technology relies on the same basic principle as those RFID readers and tags that you see all over the place in the stores right now. The main difference is that NFC operates at a shorter distance, provides secure communication, and allows for bidirectional communication (peer to peer), so it’s like an RFID solution on steroids.
It’s important to know that NFC-enabled devices can be either readers or cards. For example, when you use NFC to exchange information between two smartphones, the first smartphone begins by acting as a reader, and the second smartphone acts as a card. After the initial information exchange, they reverse roles. Now the first smartphone is a card and the second smartphone is a reader.
NFC tags can’t act as readers. They are “passive,” which means that they have no power source. So they always act as information sources, as shown here. The NFC-enabled device sends power and commands to the tag, which then responds with data.
In addition, you can use any NFC-enabled device such as a smartphone to write data to a tag using a special command. This means that you can update the tags as needed to hold new information.