If you are building a nfc reader for a custom application, the type of label you use will most likely depend on the application and the labels that can be purchased, rather than choosing a specific label type. If you want to build a custom tag, you will usually make a choice for you, because the NFC IC used for tag implementation will determine the tag type.
NFC Forum Mark Type 1
As shown by the numbers, NFC Type 1 tags are the simplest and very cheap of all NFC tag types. Typical Type 1 tags support read-only or write-once operations. However, models with R/W capabilities can be used, they usually have about a hundred bytes (maximum 2 Kbyte) of memory and have a relatively slow 106kbit/s bandwidth. Typical applications include stickers, marketing, product tracking, so these labels are of little significance to ordinary electronic engineers.
The standard adopted by NFC Type 1 tags is ISO-14443A.
NFC Forum Tag Type 2
Similar to Type 1 tags, NFC Type 2 tags only support ISO-14443A in read-only and read-write applications. Many Type 2 ICs provide energy harvesting functions and I2C connections to external microcontrollers. However, Type 2 tags are commonly used as stickers, cards and tickets.
As mentioned above, Type 2 tags are the most common tags on the market, with a wide range of shapes and sizes, and can be used for tags attached to cable ties.
NFC Forum Mark Type 3
Type 3 tags based on the Sony FeliCa protocol are mainly used in Japan and Asia. In related Japanese markets, this tag type is often used for electronic money, identification, bus tickets and similar applications. The adoption of this standard in international electronic goods is restricted, and its main purpose includes supporting older versions of applications.
NFC Forum Tag Type 4
Type 4 tags compatible with ISO-14443A and ISO-14443B protocols have added support for the ISO-7815 standard for smart card identification. These tags can modify the data contained in its memory and are commonly used in security, identification and payment applications.
NFC Forum Mark Type 5
The Type 5 label is the latest specification to be released. The underlying physical layer is different from all other NFC tag types because it is based on RFID technology (ISO-15693) instead of ISO-14443A, allowing a maximum reading distance of 1.5m. However, like any other NFC tag type, the maximum length of a customer's NFC device (such as a smart phone) is limited to 10 cm, and interaction with further places requires a special reader.
Types of NFC interaction
NFC supports three main communication modes: read/write, peer-to-peer and card emulation.
Read/write mode
The read-write mode is the simplest and most common mode of operation in the NFC standard. The NFC tag implements a memory whose content is usually composed of data in NDEF (NFC Data Exchange Format) format. Readers can read or write the contents of such memory.
The definition is very simple, but like most simple concepts in electronic products, it has a wide range of uses.
When an NFC tag has a complete SoC (System on Chip) function or is connected to an external microcontroller, it can usually be accessed not only by the reader, but also by the tag itself. In this case, the tag acts as a dual-port memory, just like a database accessed by two computers. In addition, the tag itself can be powered by the NFC reader and/or auxiliary MCU. Therefore, no matter where you visit, Tag can always be powered, just like a database hosted somewhere on the Internet.
Peer-to-peer model
In peer-to-peer mode, two active devices communicate with each other through one of the following two methods.
One device can be simulated as a tag, and another device can be simulated as a reader. This situation is obviously a master-slave solution. It is very suitable for systems with "smart" and "clumsy" parts, such as the main microcontroller communicating with a smaller auxiliary MCU through a physical barrier. This mode also allows the system to maintain compatibility with smartphones, because the smartphone itself can act as a reader, and the embedded device can act as a tag.
Realizing a peer-to-peer network through a protocol called LLCP (Logical Link Control Protocol) is a more abstract method, but it is also more flexible to connect. The LLCP protocol is designed to allow arbitrarily flexible communication between two active devices similar to BSD sockets, and many embedded and Unix programmers are familiar with this protocol. Uniquely, the LLCP protocol allows rapid migration of existing protocols, such as Modbus, RS485, CAN, LIN or UART via NFC connections, thereby realizing novel communication methods.
The disadvantage of exchanging data through the LLCP protocol is the lack of support for smart phones, which can only be delegated to embedded-to-embedded communication or embedded-to-PC. If you want to build a custom NFC application, or you can use NFC to meet project requirements without smartphone integration, then if you need a short-range wireless connection, LLCP may be what you want.
The part 1 of the depth of NFC tag types
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