Supermarket intelligent shelf management application based on RFID technology

Technology combined with the Internet and communication technology can be used in many industries such as logistics, manufacturing, and public information services. RFID has also been widely used in the Retail Industry and is progressing the fastest. A supermarket intelligent shelf management system based on RFID is proposed for the shelf management of large supermarkets. The radio frequency card is attached to the goods, and all the goods information is Stored in the central computer of the warehouse, and the information related to the goods can be checked in the computer. Readers and antennas are placed at the entrance and exit of the warehouse, and wireless relay terminals are arranged as needed to form a wireless sensor network. When goods enter and leave the warehouse, the reader placed at the entrance and exit will read the information on the radio frequency card attached to the goods and transmit it to the management center through the wireless sensor network. In this way, the management center can understand the entry and exit of the goods in real time and master the goods. According to the sales situation, the variety and quantity of the goods will be adjusted in a timely manner. Helps solve two of the biggest problems in retail: out-of-stock items and shrinkage. At the same time, consumers can go out directly without queuing in front of the checkout counter, pushing a cart full of goods, and the computer at the door will automatically print a shopping list, improving the shopping environment and increasing the competitiveness of the company.

  1

Introduction to Radio Frequency Identification Technology (RFID)

RFID technology is a non-contact automatic identification technology that uses radio waves to communicate. Radio frequency identification systems generally consist of 3 parts: transponder, reader and background database application software. The basic principle is to perform data communication through electromagnetic coupling or inductive coupling between the reading head and the tag attached to the object to achieve non-contact automatic identification of tagged items. The reader sends instructions to the antenna, and the antenna sends radio waves to "scan" the radio frequency tag. After receiving the signal, the radio frequency tag returns the data information into the form of radio waves, which is then received by the antenna and decoded into data that can be used by the computer.

  2

The overall framework design of the system

In view of the characteristics of intelligent shelf management in large supermarkets, the system mainly includes:

RFID identification system, wireless sensor network, interaction between RFID identification system and wireless terminal.

2.1 RFID radio frequency identification system

The main function of the reader is to read and write data to the transponder through the antenna and communicate with the host computer. It generally contains a radio frequency module, a control unit and a coupling element connected to the transponder. In addition, the reader has additional interfaces for transmitting the acquired data to other systems.

The reader hardware system mainly consists of 4 parts: interface circuit, control unit, radio frequency module, and antenna, as shown in Figure 1. The host computer is connected to the reader's control unit through the interface circuit, and sends read/write card and other commands to the control unit. Receive data and operation reports from the control module. The control unit is connected to the radio frequency module, and the main program running on the control unit controls the operation of the radio frequency module according to specific conditions. The radio frequency module modulates the data and sends it to the transponder through the antenna, and demodulates the transponder return signal received from the antenna.

The reader radio frequency module uses the FM1725 contactless IC card chip of Fudan Microelectronics Company, which completes the functions of data modulation and demodulation, and rectifies and transmits radio frequency modulation signals. The transmitter part inside the FM1725 chip can directly drive antennas at close operating distances without adding active circuits, while the receiver part provides a reliable demodulation and decoding circuit. Its digital processing section converts parallel data to serial, supports checking of generated frames, generates and checks parity and CRC checks, and bit encoding and processing. In addition, FM1725 also provides an SPI-compatible interface, and its parallel interface can be directly connected to the 8-bit MCU.

The control unit of the reader adopts the high-performance 8-bit microcontroller AT 89S52 produced by ATMEL Company. It is mainly responsible for running the program of reading and writing the card, providing the control signal of the FM1725 chip, and completing data communication with the host computer or network through the RS232 interface. The microcontroller contains an 8K-byte Flash read-only program memory, which is large enough to write the program for driving and controlling the FM1725 radio frequency chip. There is no need to connect other external storage devices, simplifying the circuit design and improving circuit reliability.

The radio frequency card uses the passive Mifar e standard IC card MF1 IC S50. There is an 8K-bit EEPROM in the card, which is the storage carrier of data. Data can be read and written through the antenna of the reader.

The basic operation flow is shown in Figure 2. The user first writes information into the MF1 IC S50 card through the reader. When an MF1IC S50 card enters the working range of the reader's antenna, the card is activated and the reader sends a read data signal to the card. The card sends the specified data in the storage unit to the reader through the antenna according to the received read data signal, and the reader then sends the data to the host computer or network through the RS232 interface.