Design and Implementation of Data Acquisition Network Based on RFID
1 Introduction Radio frequency identification technology RFID (Radio Frequency IdenTIficaTIon) as a high-speed development of automatic identification technology has many advantages: convenient and fast data reading, fast identification speed, can simultaneously identify multiple targets, large data capacity, long service life, application range Broadcast and tag data can be modified dynamically. Therefore, its promotion and application are more and more extensive. However, most of the readers in practical applications are only suitable for single-machine operation, not suitable for networking, and are not convenient for centralized control, and cannot be applied to multi-point high-density data collection occasions. Based on the RS485 standard, a UHF RFID reader is used to build a data collection network, and the data in the electronic tags that follow the IS018000-6B protocol solves the problem of multi-point high-density data collection. The number of network nodes can be flexibly set according to specific applications, and can be expanded up to 256 data collection nodes. The node terminal device is also equipped with a USB interface, LCD display, sound and light prompt, clock module, etc., and can also be used offline, as a general-purpose RFID reader, reading, writing tags, recording operation time, etc.
2 Overall scheme design The system draws on the classic C / S architecture in the computer network and uses the RS485 bus to connect the entire network. Among them, the computer serves as a network server, and the node terminal device serves as a client. The computer sends commands to each node terminal device to control the entire network, receives the collected data and performs further processing; the node terminal device is mainly responsible for collecting tag data and responding to computer commands. The RS485 device MAX1483 selected by the system enables the maximum number of network nodes to reach 256. The block diagram of the system scheme is shown in Figure 1.
3 hardware circuit design The focus of system design is the design of node terminal equipment, that is, the design of UHF RFID reader. The main function of the reader is to issue an interrogation signal, select the transponder in the energy field, establish a data communication link and read and write the transponder. The data collection distance of the UHF RFID reader is relatively long, which can reach 1 to 30 m. The gain and size of the RF transceiver module is set by the software to control the read and write distance, which flexibly meets the actual requirements. The reader hardware can be divided into main control module, RF transceiver module, power module, data storage module, interface part, clock module, LCD display module, sound and light prompt module and debugging circuit according to different functions, as shown in Figure 2 Show.
(1) The main control module selects the mixed-signal system-level device C8051F340 as the main control device of the node terminal equipment, which is responsible for controlling and coordinating each function module to realize data collection and command response. Use the dual serial ports of the device to control the RF transceiver module and the RS485 interface device MAX1483; the built-in USB function controller forms a USB interface; simulate the I2C timing control data storage device AT24C16 through the I / O port; control the clock DS1302 through the I / O port; The LCD transmits display data in parallel through the port, plus other I / O ports as auxiliary controls: the I / O port controls the LED and the buzzer to form a sound and light prompt module.
(2) The RF transceiver module uses RMU900 UHF read-write module. The module demodulates and decodes the signal transmitted by the radio frequency tag through the antenna, and sends the data to the main control device to realize the data collection, or encodes and modulates the command and data and sends it to the tag via the antenna to implement the write operation to the tag. The transmission of data is realized by TX0 and RX0 connected to the serial port O of C8051F340. Figure 3 is a schematic diagram of the main control template and the RF transceiver module.
(3) The power of the RF module of the power module is relatively large. Therefore, the requirements for the power supply are relatively high, requiring high output power and two different power supplies of 5 V and 3.3 V used in the entire system. So choose LT1085 as the power conversion device. The device can convert 5 V voltage to 3.3 V, and the maximum output current can reach 2 A. It fully meets the power requirements of the RF modules and other parts of the system.
(4) The data storage module stores the data collected by the node device, and then forwards the data to the computer after receiving the data sending command from the computer. The AT24C16 with I2C interface has a capacity of 16 Kbit and can store 2 Kbytes of data. Simulate I2C timing through the I / O port of the main control device to realize data reading and writing.
(5) Interface part RS485 interface uses MAX1483 device. It can drive up to 256 nodes and realize the connection with the bus through the RJ11 interface: the USB interface uses the USB controller of the main control device, which has high reliability. Figure 4 is a schematic diagram of the power supply module, data storage module, and interface section.
(6) 1602 monochrome LCD screen of other modules can display the collected data and operation time or real-time time. The display data is transmitted in parallel, which speeds up the refresh rate of the screen. The sound and light prompt module prompts the completion of the operation. Mainly control the LED flashing and buzzer whistle through the I / O port of the main control device. The clock module displays the time or real-time time of data acquisition. In addition to the onboard power supply, a spare button battery is also designed so that the clock is not lost when the power is turned off. The debugging circuit realizes online programming, writes a program to the main control device C8051F340, monitors the change of variable values, debugs the program, and assists in the completion of the software compilation. Figures 5 and 6 are the principle circuit diagrams of the above modules.
4 Software design The software design of the system includes two parts: upper computer software and lower computer software. The software part of the host computer is mainly aimed at the computer platform and is written in C ++ language. Control the node terminal device and receive the data sent by the node terminal device, and then do further processing. Considering that the maximum scale of the network is 256 nodes, the host computer uses polling to control the terminal equipment of each node to maintain the normal operation of the entire network. The commands of the terminal device of the control node mainly include: (1) Send data command: the response of the lower computer to the command is to send the collected data, that is, the data cached in the data storage module; (2) Write label command: the lower computer The response to this command is to write new data to the tag in the sensing area; (3) Time setting command: the response of the lower computer is to update the DS1302 data according to the parameters; (4) Set power command: set the RF transceiver module ’s Transmit power to adjust the distance of reading and writing tags; (5) Write extension number command: This command is a stand-alone command, which can write a unique extension number for each node terminal device to distinguish different terminal devices. The software design of the lower computer is mainly for the single-chip computer platform, written in C language, mainly the driver of each functional module, such as the control of the radio frequency module, the data reading and writing of the data storage module, the output of the clock module, the data display program of the LCD display module, USB interface driver, etc. Figure 7 is the software flow chart of the lower computer.
5 Communication protocol design Communication protocol is indispensable for the normal work of the network, mainly for the specific specification and unification of the communication frame format between the computer and the node terminal equipment, such as frame length determination, command word meaning, parameter length, frame start flag, End sign etc. Specific frame format regulations are shown in Table 1. Each frame of data has 23 bytes, of which the start bit is 1 byte, which is fixed as Oxaa; the extension number is 1 byte, and the range can be set from 0 to 255; the command is 1 byte, including 5 commands: OxOf, Ox2f, Ox4f, Ox8f, Oxaf, in order of sending data command, writing data command, time setting command, power setting command, writing extension number; 17 bytes of data, including 12 bytes of tag data and 5 bytes of time data; CRE check uses CRC- 16, a total of 2 bytes, is the CRC check value of all data between the start bit and the data bit; the stop bit is 1 byte, fixed at Ox55.
The system realizes the communication between the upper computer and the lower computer through the RS485 bus. The computer selects different node terminal devices according to the extension number, and selects the command code to implement each command. The data part is the operation response code ("0" indicates that the operation failed, "1" indicates that the operation was successful), related parameters (such as the time parameter in the time setting command ) Or return specific data (such as label data and time data).
6 Conclusion RFID technology with its advantages will be promoted and applied in the process of information construction. The system uses RFID technology to build a low-cost, high-reliability, and easy-to-maintain data acquisition network. At present, the network has been applied to a company's automatic production line. The operation condition is good, and it has wide application prospects.
Micro LED light with built-in programmed and functional IC clip inside of each LED.Each light is color changing at the same time. Colors are fuller and purer than regular RB colors.The LED light can be made to diffferent design,such as tube light,3D Acrylic Lights,bulb String Lights,string lights,christmas tree,and so on.We also have the patent of the LED bulb and it is the new technology in bulb area.Daily & festival light for indoor & outdoor decoration. Operating by low voltage for safety and convenient use.
Fip Lights
Fip Lights,LED Mini Fm Radio,PVC Reducing Bushing,Endorsed Polyurethane LED Light
Heshan Jianhao Lighting Industrial Co., Ltd. , https://www.sunclubtw.com