Research Of Fault-tolerant Dual-mode Hopping Code Decoder And Application In The Access Contorl System

With the development of society, people’s living standards are improving. The safety and reliability requirements for home access control system are also increasing. Traditional mechanical lock can not meet the needs of the market due to low security, ease of damage and other shortcomings. However, for the access control system used in special places, such as banks, stock exchanges, bio-centers and government troops department, these systems typically have more access authentication, high security and reliability, but its cost for the average consumers, is too high to cause the common consumer to bear. Development of low-end contactless smart entry system, remote access has become the focus of research and priorities.Non-contact remote keyless entry system consists of the generator and the receiver control system. The system will Microchip’s HCS300 code hopping encoder integrated into the remote control, HCS300 code hopping encoder uses KEELOQ encoding technology to encrypt data, up to 64 of its encryption keys, KEELOQ encryption technology is a non-linear encryption method such that the encrypted data is transmitted in non-repeat erratic, through confidentiality encryption technology KEELOQ encrypted data is extremely secure, thus ensuring the safety of the system.Receiving terminal control system is composed of the data module, a control module, and the drive motor module. PIC16F1823 microcontroller is inexpensive, feature rich and powerful, then the control module of the system chooses this type of microcontroller. Before the control system can perform an action, the control system must first know the transmitter information, save transmitter credentials. To improve the reliability and availability of access control system, the system uses a mechnisam of dual-mode active-standby fault-tolerance, the control system needs to identify the standby machine and own heartbeat protocol. Active-Standby protocol is used by the system to confirm the active unit and the standby unit. Under normal circumstances, a unit has two states: active or standby. When the control system receives the remote control command, the active send control commands the drive motor chip drive motor, and the backup machine does not issue a control command. Heartbeat protocol is used by the two modules to monitor each other between the two modules when the system is running. When the active does not work due to failure, the backup machine is switched to the active according to the heartbeat protocol, so that the system continues to provide services to users. According to the actual needs of users, the system offers three versions of the control system of controllable selector, so that the user can easily choose the right price and the corresponding service.Finally, the article describes the basic concepts and reliability metrics of fault-tolerant computing model, and based on the measure of reliability and availability the system is numerically evaluated.