Design And Realization Of Wireless Digital Lock Based On Code Hopping

With the development of embedded system and short-distance wireless communication technology,wireless digital lock becomes a favorite option for people to protect their ownings.Because of its security and convenience,wireless digital lock becomes part of vehicles and access control system.Based on embedded system and wireless communication technology,this thesis designs a kind of wireless digital lock with high security.Firstly,the article talks about the basic principles of designing embedded system and knowledge of wireless communication.There are two kinds of wireless lock,that is active wireless lock and its passive partner.This article uses the active one and describes a whole picture of the system.Secondly,the paper designs hardware circuit of the lock.The whole circuit consists of digital lock and digital remote key separately.The portable key is a transmitter,with its partner lock as a receiver.The transmitter is based on ATmega48P microcontroller and RF transmitter MC33493 in hardware.ATmega8L microcontroller and RF receiver MC33594 are main elements of lock circuit.Lastly,the system software is designed and programmed.Basicly,software is to realize the protocol between lock and key.As we all know,lock is used to guarantee us against invasions.The authentication algorithm is the core of security of the system and main part of system software.The design uses code hopping technology to protect the system from various invasions including "copy and replay" and "scanner".Hopping code is always realized by hardware in SOC IC,with a high patent royalty. Based on open source code,the thesis realizes the hopping code algorithm in software. After that,the hopping code algorithm is optimized both in code space and running time.