In the Internet of things, what RFID electronic tags carry is equivalent to making objects have virtual "identity" on the network. The information on RFID tags can be read through RFID readers, and the attributes, characteristics and other information of the items attached to the tags can be queried and dynamically tracked on the network in real time.

The "Internet of things" can realize global item tracking and information sharing, greatly improve management and operation efficiency, reduce costs, and bring deep changes to all links of the global supply chain (warehousing and logistics, production and manufacturing, item tracking, commercial retail, public services and other industries). To achieve these, the indispensable is RFID reader, which can collect RFID tag information "anytime, anywhere" and achieve seamless and comprehensive coverage of the Internet of things.

As an indispensable part of RFID system, RFID reader can also be divided into RFID antenna and RFID reader. The RFID reader / writer sends signals to "wake up" and transmit instructions to the RFID tag through the RFID antenna, and receives the signal returned by the RFID tag. After preliminary filtering and signal processing, complete the acquisition and analysis of RFID tag information, and interact with the data management system through the network. The data management system can be a simple local software or a distributed ERP management software integrated with RFID management module.

The communication process of RFID system is the process of RFID reader giving RFID tag information and obtaining the information on the tag. Since the passive RFID tag itself has no power supply, it must rely on the energy obtained from the RF signal sent by the RFID reader (beam power supply technology), while the energy obtained by the RFID tag is only enough to supply the electronic tag itself, and there is no excess energy for the RF signal source to work. Passive reflection modulation technology must be used to realize the communication between the RFID reader and the RFID tag. The RFID tag modulates the continuous wave RF signal transmitted by the reader during the response process, and then reflects the modulated RF signal back, which is received and decoded by the reader to complete the information transmission function.

Composition of RFID Reader:

RFID reader is generally composed of RF module, control processing module and antenna. The RF module is mainly responsible for the conversion between RF signal and baseband signal and the modulation and demodulation of data information; As the core of RFID reader and writer, the control and processing module is mainly responsible for the communication management with the platform system and RFID tags, the encoding and decoding of baseband signals, the implementation of anti-collision algorithms, encryption and decryption in the process of data transmission, identity authentication, and the control of external devices; The function of the antenna is mainly responsible for receiving or sending RF signals to realize the transmission of data information and energy.

Functions of RFID reader / writer:

1. Be responsible for communicating with RFID tags, initializing RFID tags, reading and writing data information in RFID tags, and managing RFID tags, such as disabling their functions;

2. It is responsible for the communication with the computer platform system. On the one hand, it transmits the data information read from the RFID electronic tag to the platform, on the other hand, it receives the control information of the platform system to complete specific application actions;

3. It transmits energy to passive RFID tags through radio frequency. For active tags, it can also read the relevant information of the built-in battery of RFID tags, such as power.

4. RFID readers are easy to install and can generally be managed and controlled by application software, so they can be maintained remotely;

5. RFID reader / writer has the ability of anti-collision to identify multiple tags, can identify multiple mobile electronic tags, can complete the simultaneous access of multiple tags, and has the ability of anti-collision of information read by multiple tags at the same time;

6. RFID reader has strong compatibility, compatible with the most common communication protocol, and can communicate with a variety of electronic tags.

Structure of RFID reader / writer:

The structure of RFID reader and writer has no fixed form. It mainly designs the structure and appearance shape of RFID reader and writer according to needs and application scenarios. Common RFID readers and writers mainly include fixed RFID reader and writer, handheld reader and writer, integrated reader and writer, separated component reader and writer, industrial reader head, OEM modular reader and writer, etc.

Implementation method of each function of RFID reader / writer:

1. Event scheduling

PIC32 chip is used to realize simple RFID identification, display and communication event scheduling functions.

2. External communication

Use PMOD NIC peripheral module to realize Ethernet communication function.

3. RFID signal processing

PIC32 chip is used to realize the basic functions of signal sampling, shaping, digital filtering and decoding.

4. Human machine interface

All event scheduling information, debugging information and identified RFID tag ID numbers are displayed to the operator through the PMOD CLS peripheral module.

Parameters of RFID reader / writer:

1. Output power

This parameter is related to the application. On the one hand, it should meet the needs of the application, on the other hand, it should also meet the regulatory requirements, that is, to meet the wireless frequency specifications and health requirements.

2. Working mode

It is divided into full duplex, half duplex and timing.

3. Operating frequency

It is consistent with the working frequency of RFID electronic tag, but the frequency of RFID system is generally determined by the frequency of RFID reader.

4. Output interface

Common interfaces include 5g, 4G, WiFi, USB, RS-485, RS-232, etc., which can be selected according to the needs of the scene.

5. Priority mode

It is divided into RFID reader priority and RFID tag priority. RFID reader priority means that RFID reader first sends RF energy and commands to RFID tag, while RFID tag priority means that RFID reader only sends RF energy with equal amplitude and no information. Both of them start receiving commands and sending data information after RFID tag is activated.