How to use NFC in everyday life – OnLime Blog

Types of NFC tags

There are four types of tags described by the NFC forum, all based on RFID protocols. This makes NFC tags partially compatible with many existing RFID systems (eg Mifare and FeliCa). Although these older systems do not support NDEF, they can still recognize NFC tags that are compatible with them.

For example, an RFID reader that is designed to work with Mifare Ultralight tags can read the ID number of an NFC type 2 tag, although it cannot read NDEF encoded information. There is also a fifth type that is compatible with the technology but is not part of the NFC specification.

Types 1, 2 and 4 are based on GOST R ISO/IEC 14443A (consists of four parts: 1, 2, 3, 4), type 3 is based on GOST R ISO/IEC 18092. More details about each of the types can be read under the spoiler.

Where NFC is used

Many have heard that this technology allows you to quickly and contactlessly pay for goods and services. In fact, its scope is much wider and includes:

• transferring files, such as photos or audio, from one smartphone to another;
• access to private data – when NFC is used as an electronic key;
• for identity verification – when NFC will contain personal information about the owner of the device;
• to transfer funds from one smartphone to another – only if both devices have NFC;
• to output video from a smartphone to a TV – for this, it is necessary that both the mobile device and the remote control are equipped with the appropriate chip;
• for reading special tags – any information can be encrypted in them: contacts of a company or person, address, link to a website, etc.

How it works

NFC works in a similar way to Bluetooth, but when connected to another NFC device, it does not take much time to identify, the connection is established almost instantly (in tenths of a second).

NFC is a short-range wireless technology that operates at a frequency of 13.56 MHz used for industrial, medical and scientific applications. N FC is a logical continuation of RFID technology, and its main difference is a limited range. While the reading distance of RFID tags can reach several hundred meters, NFC tags are available within 10 centimeters.

NFC always has an initiator and a target. The initiator actively generates an RF field that can affect the passive target. NFC communication between two devices is also possible, provided that both devices are turned on. Due to its compact size and low power consumption, NFC can be used in small gadgets[1].

For data transmission, NFC uses coding with different modulation ratio depending on the data rate. At the same time, NFC devices are able to simultaneously receive and transmit data. Thus, they can monitor the RF field and detect inconsistencies if the received signal does not match the transmitted one.

NFC, like RFID, has an initiator and a target in the exchange, but the new technology allows much more than a simple exchange of an identifier and reading or writing information of the target. The most significant difference between the two technologies is that NFC targets are often programmable devices such as smartphones. This means that it is possible to exchange not only static data, but also generate a response to the information requested by the initiator each time.

NFC devices have two interaction modes. If the initiator emits radio frequency waves, and the target receives power at the expense of the initiator, then this mode of interaction is called passive. In active mode, the initiator and target have their own power supplies and are independent of each other. These modes are the same as RFID modes.

NFC devices also have three ways of working. They can work in the mode of reading information from the target or writing to it. They can emulate cards by acting like RFID tags when they are in the field of another NFC or RFID device. Or they can work in peer-to-peer (P2P) mode, in which they exchange data in both directions at once.

The first main difference between NFC and RFID is the peer-to-peer interaction method, which is implemented using GOST R ISO / IEC 18092. P2P data exchange is implemented by two protocols – the logical link control protocol (LLCP) and a simple NDEF data exchange protocol (SNEP – simple NDEF exchange format).

Pluses and minuses of the module

• Security. Since the range of the chip is limited to 10 cm, no one outside this circle will have access to payment data or transferred files.
• Connection speed. It takes less than one second for a device to connect to another gadget or terminal. In older mobile phones and early smartphones, this procedure took up to 15 seconds.
• Energy efficiency. The NFC chip uses a minimal amount of power in operation. This is important in modern smartphones, which do not show the highest autonomy.
• Convenience. With this technology, routine operations are simplified, and you spend less time on them. To establish a connection with another device, a simple second touch is enough.
• Versatility. NFC technology is compatible with many other contactless solutions and can work (albeit with limitations) even when the smartphone is turned off.

Among the main advantages are low energy consumption, reasonable price, ease of use and safety. But before you start using NFC, you need to familiarize yourself with some of the nuances.

Let’s analyze the main disadvantages of NFC.

1. Small working radius. This brings some discomfort when using. Although, at the same time, this indicator creates maximum protection. You will not be able to randomly produce a command, pay for a purchase, etc.
2. Uncontrolled creation of modifications for NFC. For example, the developers of Sony and Haomi took up the finalization of the transmission technology. They independently make consumables that carry out their work only with the gadgets of their company. In other words, in order to use all the NFC options, you will only have to purchase smartphones of specific brands. This also includes the installation of special applications from the same developer.

Some of the shortcomings are corrected gradually. Developers do not abandon their technology and constantly make various improvements.

NFC architecture

There are several layers in the NFC architecture. The lowest of them is the physical one, which is implemented by the CPU and other hardware complex through which the interaction takes place. In the middle is the packet data and the transport layer, then the layer data format, and finally the software.

At the physical layer, NFC works according to the algorithm described in GOST for RFID (GOST R ISO / IEC 14443-2-2014), which refers to low-power radio signals with a frequency of 13.56 MHz. Then comes the level that describes the breakdown of the data stream into frames (GOST R ISO / IEC 14443-3-2014). Any radio controllers that are used in a phone, tablet, or connected to a computer or microcontroller are separate hardware components.

They communicate with the main processor through one or more standard serial protocols between devices: Universal Asynchronous Transceiver (UART), Serial Peripheral Interface (SPI), Serial Data Bus for Integrated Circuit Communications (I2C), or Universal Serial Bus (USB) .

Above this are several RFID command protocols based on two specifications. N FC tag reading and writing is based on the original RFID GOST R ISO/IEC 14443A. The Philips/NXP Semiconductors Mifare Classic and Mifare Ultralight and NXP DESFire protocols are compliant with GOST R ISO/IEC 14443A. P2P NFC data exchange is based on GOST R ISO/IEC 18092.

They are depicted in the figure above on a par with other control protocols, since they use the same standard.

How to activate NFC on your smartphone

Open the settings menu of the mobile device, select the “Wireless networks” / “Wireless communications” section and find the item of the same name there. Most often, it is hidden in the “More …” tab. To activate the function, simply check the box that allows the exchange of information when the smartphone approaches another device or terminal.

If there is no NFC item in the section with a list of wireless networks, then the smartphone does not have this chip. Many manufacturers of mobile gadgets advertise this feature and place the name about it on batteries or back covers (as in Samsung), or even directly on the body (as in Sony). However, this is more of an exception than the rule.

The above methods are only suitable for Android smartphones. In Apple devices, the NFC chip appeared in the iPhone 6. At first, it was used only for the Apple Pay service, but in the latest smartphone models, the reading mode is additionally supported.

Creating Common NDEF Records

NDEF is used to format exchange data between devices and tags. This format typifies all messages that are used in NFC, and it does not matter for the card or for the device. Each NDEF message contains one or more NDEF entries. Each of them contains a unique record type, an identifier, a length, and a field for the information to be reported.

There are several common types of NDEF records:

1. Plain text entries. Any string can be sent to them, they do not contain instructions for the target, but contain metadata about the language of the text and the encoding.
2. URI. Such records contain data about Internet links. A target that receives such an entry will open it in an application that can display it. For example, a web browser.
3. Smart recording. Contains not only web links, but also a text description for them, so that it is clear what is located on this link. Depending on the recording data, the phone can open the information in the desired application, be it SMS or e-mail, or change the phone settings (sound volume, screen brightness, etc.).
4. Signature. It allows you to prove that the information that has been transmitted or is being transmitted is reliable.

You can use multiple record types in one NDEF message.

You can think of a message as a paragraph and notes as sentences. A paragraph is a specific unit of information that contains one or more sentences. Whereas a sentence is a smaller unit of information that contains just one idea. For example, you can make birthday invitations in the form of a paragraph and write information about the date, time and place of the event in separate sentences, and use NDEF messages to send friends a reminder of this event, where there will be a text message describing the event, a smart entry with a place and a web link on how to get to that location.

The second main difference between NFC and RFID is NFC data exchange format (NDEF). N DEF defines the format of data in messages, which in turn consist of NDEF records. There are several types of records, which will be discussed in more detail below. N DEF makes it possible to use code to control the process of reading and writing NFC tags, peer-to-peer communication, and card emulation.

NDEF contains information about the byte representation of messages that can contain multiple entries. Each entry has a header that contains metadata (type, length, etc.) and information to send. If we return to the analogy with the paragraph, then the paragraph is formed from sentences related to the same topic, and in NDEF messages – it’s good when all entries relate to the same topic.

NDEF messages are mostly short, each exchange consists of one message, each label also contains one message. Since the exchange of NFC data occurs when one device is touched by another or by a label, it will be inconvenient to transmit the text of an entire book in one message, so the length of an NDEF message is comparable to the length of a paragraph, but not the entire book.

An NDEF record contains information to forward and metadata on how to interpret that information. Each entry can be of a different type, which is announced in the title of that entry. The header also describes what place the record occupies in the message, after the header information follows. The figure below shows complete information about the location of bits and bytes of information in the NDEF record.

The space for information in an NDEF record is limited to 2^32-1 bytes, but you can chain records within a message to send larger information. In theory, there are no restrictions on NDEF messages, but in practice, the message size is limited by the capabilities of the devices or tags involved in the exchange of information.

If only devices are involved in the exchange, then the length of the message will be limited by the computing power of the weakest of the devices, but it is worth considering that the devices will have to be kept nearby for a long time to send all the data. When the smartphone and the card interact, the length of the message will be limited by the memory size of the card.

In general, data exchange via NFC is quite fast. The person brings the mobile device to the tag, there is a brief exchange of information, and the person moves on. This technology was not designed for long exchanges of information, because the devices literally have to be a couple of centimeters apart.

In order to transmit a large amount of information, the devices will have to be kept next to each other for a long time, this may be inconvenient. If you need a long interaction between devices, then you can use NFC to quickly exchange data about the capabilities of devices and then turn on one of the more suitable data transfer methods (Bluetooth, Wi-Fi, etc.).

When an Android phone reads an NFC tag, it first processes and recognizes it, and then transfers the data about it to the appropriate application for the subsequent creation of an intent. If more than one application can work with NFC, the application selection menu will appear. The recognition system is defined by three intents, which are listed in order of importance from highest to lowest:

1. ACTION_NDEF_DISCOVERED: This intent is used to start an activity if the label contains an NDEF message. It has the highest priority and the system will run it first.
2. ACTION_TECH_DISCOVERED: If no activity is registered for an ACTION_NDEF_DISCOVERED intent, then the recognition system will try to launch an application with that intent. Also, this intent will be fired immediately if the found NDEF message does not match the MIME type or URI, or the label does not contain a message at all.
3. ACTION_TAG_DISCOVERED: This intent will fire if the previous two intents failed.

In general, the recognition system works as shown in the figure below.

When possible, the ACTION_NDEF_DISCOVERED intent is fired because it is the most specific of the three. Moreover, with its help it will be possible to launch your application.

If an activity is launched due to an NFC intent, then you can get information from the scanned NFC tag from this intent. Intent may contain the following additional fields (depending on the type of scanned tag):

• EXTRA_TAG (mandatory): Tag object describing the scanned tag.
• EXTRA_NDEF_MESSAGES (optional): Array of NDEF messages calculated from the label. This extra field is specific to the ACTION_NDEF_DISCOVERED intent only.
• EXTRA_ID (optional): Low-level label ID.

Below is an example that checks the intent ACTION_NDEF_DISCOVERED and gets NDEF messages from the extra field.

Kotlin

 override fun onNewIntent(intent: Intent) {
 super.onNewIntent(intent)
 .
 if (NfcAdapter.ACTION_NDEF_DISCOVERED == intent.action) {
 intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES)?also { rawMessages -{amp}gt;
 val messages: List = rawMessages.map { it as NdefMessage }
 // Processing the array of messages.
 .
 }
 }
} 

 @Override
protected void onNewIntent(Intent intent) {
 super.onNewIntent(intent);
 .
 if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(intent.getAction())) {
 Parcelable[] rawMessages =
 intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
 if (rawMessages != null) {
 NdefMessage[] messages = new NdefMessage[rawMessages.length];
 for (int i = 0; i {amp}lt; rawMessages.length; i ) {
 messages[i] = (NdefMessage) rawMessages[i];
 }
 // Processing the array of messages.
 .
 }
 }
} 

Kotlin

val tag: Tag = intent.getParcelableExtra(NfcAdapter. EXTRA_TAG)

Tag tag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);

There are several methods for creating an NDEF entry: createUri(), createExternal() and createMime(). It is better to use one of them in order to avoid errors that may occur when creating a record manually. All examples below should be sent as the first message when writing a tag, or by pairing with another device.

Kotlin

NFC communication

The technology can also be used to transfer files.

To transfer data, you need to do the following steps:

1. make sure that you have completed the activation of NFC and Android Beam;
2. unlock the device, exit the “sleep mode”;
3. check device detection with each other;
4. connect;
5. transfer data between devices;
6. a specific beep will sound at the end.

This is the most popular way to use technology, so let’s take a closer look at it. You can attach a bank card to an NFC-enabled smartphone and then touch the gadget to payment terminals to pay for goods and services. You do not need to use the card itself – it can easily lie in your wallet or at home. This service will be available in all POS-terminals that support payment by contactless cards.

This option is available on Android Beam-enabled smartphones on Android devices version 4.0 Ice Cream Sandwich or later. From one smartphone to another, you can send any information: a photo, user contacts, a link to a website or a video. You save a lot of time, because you no longer have to use cloud storage, email or instant messengers for this.

To start transferring data via NFC, follow these steps:

• unlock both smartphones;
• activate NFC in them, and Android Beam will start automatically;
• open the file, contact or other content you want to share;
• place the smartphones with their covers facing each other at a distance of up to 10 cm;
• wait for connection.

Sending data will start after you tap the display of the transmitting smartphone. Keep the devices as close as possible to each other until the transfer is over – you will know about this by sound notification.

Creating Common NDEF Records

Not only to read, but also to create tags, you can use this technology. In this case, its principle of operation is somewhat similar to the creation and reading of QR codes, but without the use of a smartphone photomodule.

The following actions can be the result of reading the tag:

• sending an SMS message or email;
• enable or disable Wi-Fi and Bluetooth;
• connection with another device via Bluetooth protocol;
• putting the smartphone into “flight mode”;
• launch of a mobile application;
• follow the link and many others.

What is Google Pay and Apple Pay?

Today Google Pay, and until February 2018 – Android Pay is a system of electronic payments from mobile devices running on Android. Not only smartphones work with it, but also tablets, smart watches and other gadgets. The number of countries in which the service operates is approaching twenty. Russia joined them on May 23, 2017, and among the first were the United States, Great Britain and Singapore.

Android Pay is based on NFC payment, which replaces a PIN chip or magnetic strip on a bank card. There are two ways to add card data to the application: enter it manually or simply take a picture of both sides of the card with the smartphone’s built-in camera.

Making payments with Android Pay is easy: just bring your mobile device to the payment terminal and don’t remove it until the transaction is completed. To do this, it is necessary that the cash register be equipped with a modern NFC-enabled terminal.

How does a smartphone know that it is the owner of the gadget who pays for purchases? To do this, different methods of identity verification are used: a password, a fingerprint scanner or an iris scanner. For security reasons, payment card data is not transferred to the merchant – the latter receives only the generated virtual account number.

Apple Pay, a mobile payment system from Apple, works in a similar way. It has been available in Russia since October 2016 (in general, in almost 30 countries of the world) on iPhone 6 and older smartphones. As in the case of Google Pay, it uses the technology of “near contactless communication”, and the principle of operation of both systems is identical except for a few details. After the bank card is digitized by the Apple Pay app, you can pay with it where POS terminals allow it.

With a high probability, NFC technology will continue to develop and be actively introduced into our lives. Analysts predict its popularity not only as a means of payment, but also as a means of disseminating information about objects of culture, healthcare, tourism, as well as a means of access control.

Have you already tried using NFC in your smartphone?

Conclusion

Today, NFC is a modern solution for sending information. But not all smartphones support this technology. If your phone is not modified, then you can purchase a special antenna yourself. Install it under the cover of the gadget or take the spare parts to a service where a specialist will do everything for you.

Another way to get to know NFC personally is to buy a special accessory. Today, many companies offer to purchase memory cards, SIM cards, where the NFC is built in.

The prevalence of NFC has not reached impressive results, but this is not for long. Now it is mainly used for monetary transactions, although there are other areas of application. The main advantage of the modification is safety. Its principle of operation excludes accidental transfers of data and money to other devices.

NFC technology adds promising functionality to RFID technology. The most significant innovation is the NFC Data Interchange Format (NDEF), which provides the ability to format regular data into one of four NFC tag technologies. N DEF can be used both for data exchange between a device and a tag, and for exchange between devices. This makes NFC suitable not only as a method of identification, but also as a means of exchanging short blocks of data.

https://www.youtube.com/watch?v=85oWPy-vsz4

For more information about NFC or NDEF, see Tom Igoe, Don Coleman, and Brian Jepson Beginning NFC. Near Field Communication with Arduino, Android, and PhoneGap.