Research Of UHF RFID Reader Based On Specific Integrated Chip AS3991

ABSTRACT:RFID is short for Radio Frequency Identification. It transmits information wirelessly using radio waves, and identifies the object without contact. The RFID system includes reader, tag, middleware, and database system. When the RFID system works, the reader transmits the wireless carrier signal by antenna. After the tag has been activated, the information of the tag, as a modulation code, will be transmitted by backscatter. Then the reader demodulates the signal and decodes, and passes the data to the database for processing. During the identification process, no manual intervention is needed, and tag does not need visualization. The fast moving objects can also be identified. And it can work in a lot of complex environment. So the RFID technology is widely applied in transportation, logistic, medicine management, animal management and so on. Particularly, RFID working in the UHF band, can identify the tag more quickly, and has father identification. It is more suitable for logistic and supply chain. So it has got more and more application and attention.This paper analyzes the characteristics of UHF RFID technology and ISO18000-6C protocol standard. Then the paper proposes a UHF RFID reader design based on ARM, the operating frequency of reader is 915MHz. The design scheme selects AS3991 as the radio IC, which is released by Austria Microsystems. AS3991 is designed specially for UHF RFID reader. It integrated transmission circuit, receiver circuit, protocol process unit. It not only supports ISO18000-6C protocol, but also has compatible with ISO18000-6A/B protocol. Parallel or serial interface can be selected for communication between the host system and the chip. The Samsung's S3C2410 is selected as MCU, with low power consumption. It has fast data process capabilities. Using Windows CE as operating system, it makes the application program development simple. And the scheme has good compatibility and portability. The scheme improves the peripheral circuits, adds PA circuit, making the reader have father work distance. It provides the API for the upper application program. Compared with the existing RFID readers, the design can make the reader smaller, read the tag faster, and the MCU process data faster.