Implent Of CAN Bus And PSD Module In Center Sicnal Screen

In the system of relay protection of electric power, abnormal state information given by relay protection devices has two types: accident information message and warning information message. Accident information message is about action information message of relay switching; warning information message is about alarm information message sent by relay protection devices. In order to receive abnormal state information message, at the same time in order to make field operators know immediately running state of relay protection devices, usually there is an additional set—center signal screen.Design method of center signal screen was relay wiring logic, which is waste of time and effort, which had been replaced. And now design method of based on MCU not only increases working performance, but also saves design overhead.Wiring net of field is use of CAN field control bus that is uniqueon international standard. It is a kind of high-speed communication bus faces to general industrial devices, which has many merits: simple data and structure, strong reliability. It meets to communication demand from lots of industrial devices, and supports the distributed control system, and has excellent ability of real time, and is a kind of computer area network based on bus and fitting to automation control from industrial field.μPSD3234A produced by ST Company is a new kind of MCU based on 8032 core, and integrates PSD module including SOC characteristic. PSD is field programmable micro controller peripheral chip and a kind of ideal peripheral extension chip suiting to MCU. It makes many peripheral chips need by MCU integrated, such as address latch EPROM or FLASH SRAM PLD and so on, which greatly simplifies hardware circuit and makes design modification and extension become more flexible.According to USB module and I2C interface integrated by μPSD3234A, center signal screen has communication circuit fitting to USB 1.1 protocol and μP power supervisory circuit including EEPROM programmable WATCHDOG so which increases ability ofsystem extension and enhances stability.This paper introduces communication theory of CAN bus and function characteristic of PSD module, so mainly deals with hardware design scheme on CAN and PSD ,and the other functions modules, and provides implement method of USB driver program and initialization flow chart of CAN bus controller.