Design scheme of smart refrigerator based on RFID,RFID Syringe manufacturer

　　Design scheme of smart refrigerator based on RFID

　　With the rapid development of people’s living standards and the accelerating pace of life, the refrigerator plays an increasingly important role in the family, but it is troublesome to organize. At the same time, it is often unclear whether the food is used up or some food is forgotten in the refrigerator. Cause all kinds of troubles in life.

　　With the development of the Internet of Things, the investment in smart homes for the Internet of Things is rapidly expanding, and the finished products of RFID tags are also continuously decreasing. In the future, it may replace barcodes as food outsourcing. Moreover, RFID tags are known for their durability, durability and maintenance-free. As most people's families have reached the conditions of a well-off level, they are eager for more convenient and labor-saving home appliances. Although this system is just a rudimentary form, the price is moderate, and it uses more cutting-edge technology, which is more trouble-free than traditional refrigerators. It provides convenience for the busy life of urban people, solves many trivial things in life, and will be introduced to the market for most people. Accepted.

　　1 System overall scheme design

　　1.1 Overall system plan

　　According to the function and technical requirements of the smart refrigerator terminal, it was decided to adopt the system structure of "hardware + software" to design the smart refrigerator terminal. The application layer was written according to the different needs of the project on the basis of the OS. Each part is briefly introduced as follows:

　　The system is selected based on the hardware development platform using Intel Xscale PXA270, which is an ARM processor with Intel XScale architecture.

　　Windows CE 5.0 is selected as the embedded operating system. Windows CE is a highly modular embedded operating system, and users can customize and cut them through the Platform Builder tool according to their own equipment requirements.

　　Application framework: qt-embedded-wince-opensource4.6 has a rich standard library, a dynamic engine, a Widget style sheet, powerful graphics layout and multi-threading functions; it achieves high performance and small footprint on Windows CE .

　　This system is used as a household electrical appliance. It can query food and go online at any time through the Internet. Users can learn about refrigerator food information through SMS and decide whether to buy it online. Figure 1 of the overall system scheme is as follows.

　　1.2 System Module

　　According to the design plan, we divide the whole system into three main modules, as shown in Figure 2.

　　Figure 2 System module diagram

　　1.3 Detailed description of module functions

　　(1) Food status module.

　　Table 1

　　(2) Online shopping module.

　　Table 2

　　(3) Recipe module.

　　table 3

　　2. Hardware design

　　2.1 RFID reader, antenna module

　　ISO18000-6C I series readers are a new generation of long-distance electronic tag readers independently developed by Shenzhen First Technology Co., Ltd. The tags supported by the readers mainly comply with ISO18000-6C (hereinafter referred to as "6C") Passive electronic label of the agreement. Users can use this reader to read, write, and lock 6C electronic tags. The reader has three working modes of reading electronic tags: master-slave, timing and trigger. The communication interfaces connecting the host and the controller are RS-232, RS-485 and Wiegand interfaces. It can be directly connected to a control device with a standard Wiegand W26 or W34 interface, or it can be connected to a controller or PC through a standard communication interface for data communication and exchange; in addition, there are four trigger signal input interfaces. When the pressure sensor detects a change in the pressure in the refrigerator, the corresponding function is triggered to make the reader scan the food label in the refrigerator. At the same time, the module provides read and write multiple tags at a time, which is suitable for the design of this project.

　　2.2 GPRS/GSM module

　　This module adopts Hongpeng Electronics Co., Ltd. DU600, which supports multiple connection modes and can realize the basic functions of mobile phone communication. The GPRS module of the smart refrigerator only needs to send and receive text messages and interpret the received text messages. Only the DU600 needs to select the wake-up mode to wait for the text messages and send control commands to the PXA270 through the commands obtained after interpreting the text messages to realize the purchase function and query function.

　　2.3 Pressure sensor module

　　Through 89C51 single-chip microcomputer, it integrates LCD module, serial port module and 24-bit ADC module. This module is mainly responsible for sensing pressure changes and sending interrupt signals to the central control platform through the serial port.

　　The pressure sensor HX711 adopts the patented technology of Haixin Technology's integrated circuit and is a 24-bit A/D converter chip specially designed for high-precision electronic scales. When the pressure sensor changes, it will send a signal to the core board to indicate that there is a change in the refrigerator and start RFID scanning.

　　2.4 Temperature control module

　　This module is a refrigeration control system based on a single-chip microcomputer, with real-time temperature display and adjustable refrigeration temperature, down to minus 10 degrees.

　　The temperature sensor of this module adopts DS18B20. According to the communication protocol of DS18B20, the host (microcontroller) controls the DS18B20 to complete the temperature conversion and must go through three steps: reset the DS18B20 before each read and write, and send a ROM command after the reset is successful. Finally, send the RAM command, so that the DS18B20 can perform the predetermined operation. The reset requires the main CPU to pull down the data line for 500 microseconds and then release it. When DS18B20 receives the signal, it waits for about 16 to 60 microseconds, and then sends out a low pulse of 60 to 240 microseconds. The main CPU receives this signal to indicate a successful reset . At the same time, this module uses a semiconductor refrigeration chip to realize the fresh-keeping function of a simulated refrigerator.

　　3 software design

　　The software block diagram of the smart refrigerator based on Windows CE 5.0 is shown in Figure 6.

　　3.2 Application development

　　(1) RFID realization process.

　　Use the RFID API function ReadID to read the RFID card in the refrigerator, and read the RFID card multiple times in succession. During the reading period, the anti-collision algorithm is used to eliminate the same RFID card information read, and then the obtained RFID card information is stored in the data structure, so that the data structure can be used to check with the database data in the future. After reading, disconnect the RFID connection and start to compare data with the database.

　　Here we use the current extensive binary tree anti-collision algorithm. When data exchange between the reader and the transponder, part or all of the serial number is often transmitted. The transmission sequence at this time is defined as: send the low bit first, then send the high bit. In the reader or transponder, when comparing data, follow the principle of comparing bit by bit, first compare the low bit, then compare the high bit. The agreement is 0<1. According to this comparison order, when judging the size, the low bit Data priority means that the two numbers A and B are compared. The size of the first unequal bit from the low bit determines the size of the two numbers. The two numbers are equal only when all the bits of the two numbers are equal. During the execution of the binary tree algorithm, the reader will send multiple times to divide the transponder into two groups and get the only one transponder command to the transponder after multiple groupings, and the command parameters are stored in the form of nodes during this grouping process The binary tree anti-collision algorithm of the smart refrigerator is compared in the transponder, because there can be multiple readers, and the data read by the reader is sent to The transponder, therefore, choose the transponder as the burning place of the anti-collision algorithm, so that the transponder can transmit the label data to the main control platform PXA270 after the transponder accepts the tag read by the reader and excludes the same.

　　(2) GPRS realization process

　　After receiving the database comparison and requesting shopping list, run the GPRS program written in C++ code through QT. First get the information data that needs to be sent to the customer from QT, and then use OnBnClickedBtnOpen () to configure the RS-232 serial port connection to configure GPRS, and wait for the GPRS connection to succeed.

　　When the connection is successful, GPRS will return "AT+OPENAT=MODE:3#" to confirm that the connection is successful. Then send the message to GPRS through the OnBnClicked -BtnSend (string) function, and then GPRS will send the message to the customer's mobile phone according to the content of the message. After the transmission is successful, GPRS will wait for 5 minutes to wait for the customer to send a reply to confirm the purchase.

　　If the customer does not reply to confirm the purchase within 5 minutes, the food purchase will be automatically cancelled and the GPRS connection will be disconnected; if the customer replies to confirm the purchase within 5 minutes, the program will return a purchase confirmation message and disconnect the GPRS connection.

　　(3) Pressure sensor realization process

　　When the refrigerator is opened, PXA270 energizes the pressure sensor. The pressure sensor will record the initial gravity when it works for the first time. When the refrigerator is closed, measure the gravity of the pressure sensor and compare the initial gravity to see if it has changed. If it has not changed, close the pressure sensor and disconnect the pressure sensor ID reader.

　　(4) The temperature control realization process

　　Due to the problem of the PXA270 external socket, the temperature sensor is based on a single-chip microcomputer and does not need to be embedded on the PAX270 development board. The temperature sensor will start with the start of the refrigerator. When the data measured by the temperature sensor is sent to the single-chip microcomputer, the single-chip microcomputer will first compare the temperature in the refrigerator with the set temperature of the refrigerator, and turn on the refrigeration device if it is higher than the temperature of the refrigerator. During the cooling period, the temperature of the refrigerator is also continuously measured and compared with the set refrigerator temperature; if the temperature is less than or equal to the set temperature of the refrigerator, the refrigeration device is turned off. The single chip microcomputer continues to receive the temperature of the refrigerator from the temperature sensor and compares the set temperature of the refrigerator to prepare to open the refrigeration at any time to maintain the temperature of the refrigerator. When the refrigerator is powered off, the MCU will stop running and the refrigerator will be turned on again after the refrigerator is powered on and the MCU will be initialized from the beginning.

　　(5) Online shopping process

　　In this process, we designated the Internet of Things supermarket website that the refrigerator can directly access, so as to connect. Therefore, in this project, we built a shopping website (ASP) by ourselves in order to interact with such products. By calling the function HINTERNET InternetOpenUrl() in the header file that comes with the system to open a complete FTP, Gopher or HTTP URL resource, you can get the product-related information.

　　In addition, users need to log in to the shopping website to place an order. Here, we default that each smart refrigerator is equipped with a dedicated account to bind and log in, and the page is submitted through POST. When the refrigerator is successfully logged in, you can purchase goods and place an order.

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