Design Of Active RFID System Based On ARM_Linux And Solar Charging

2.45 GHz Active RFID system has many advantages, such as long-distance communication, small-size antenna and registration free band. With the gradual advance of 2.45 GHz ISO/IEC18000-4 standards, which is organized by the UESTC, 2.45 GHz RFID system in the domestic is bound to be promoted. When it comes to track or monitor outdoor objects by existing active RFID systems, it is undeniable that they have many deficiencies in energy conservation, management and practicability. Considering these, an active RFID system has been designed, which bases on ARM-Linux and solar charging. It uses environmentally friendly solar power, with anti-demolition, anti-collision function, as well as efficient management of Bluetooth alarm and remote network access.Firstly, the development of RFID technology and some ways to gain energy from the environment are analyzed. Then a detailed analysis of the needs in the practical application of the RFID system, and based on these the framework of the system has been designed. In the design of active RFID tag, the host controller chip and RF chip have been discussed. Finally, the system adopts MSP430F2121 as the host controller, nRF24L01 chip as the core of the RF modules, solar cells and lithium batteries as the energy supply and energy storage components. Thanks to the CN3063 battery management chip makes the solar power system to charge and discharge management automatically. Voltage of the solar power system has been tested, as proved to be the power supply for the RFID tag. This solar power system extends the life of active RFID tag.The anti-demolition and anti-collision functions have been studied. Using of a switch to control the state of the object which we track or monitor. To make this alarm inform management quickly, a Bluetooth module has been connected to the periphery of the reader, through which the alarm is sent to mobile phones. The system adopts ALOHA algorithm and pre-assigned channels to reduce the probability of packet collisions.As for the reader, using S3C2440 A as CPU, DM9000 as Ethernet controller, while porting Linux embedded operating system, BOA Web server, SQLite3 database and the driver of nRF24L01 RF module. In CGI program, commands are passed to RF receiving by Posix message queues. Multithreading technology is used to process the received data. The reader uses database to store data from tags. After writing HTML applications, users can get temperature information by web browser.Finally, on the theory and practice of RFID antenna, communication distance is analyzed, the entire system works in good condition, the maximum communication distance between reader and RFID tags can reach 120 m, and the distance will decreases when there are something hinder them.