Design And Realization Of Hardware Of OBU In ETC System

ETC(Electronic toll collection) system as the most advanced intelligent charging system, has been being popularized in the highways, bridges and tunnels. The system is based on the DSRC (Dedicated Short Range Communication) standard, mainly consists of two part, RSU (Road Side Unit) and OBU(on board unit). Via the5.8GHz wireless communication between vehicle and toll station, electronic toll collection is completed and realize the information exchange between the vehicle and the road network.This subject designed and realized the OBU. first introducing the foreign and domestic development status of the ETC system, and according to the composition of the OBU in ETC system, the communication process as well as the physical layer protocol specification of DSRC dedicated short-range communication, this paper complete the overall design of OBU which combine "ESAM&IC card module+communication module" from the functions design and divide into digital processing part and radio frequency part from the structural design.Digital processing part is mainly composed of the MCU(micro control unit), the ESAM&IC card module and the expanding application modules. Application TI corporation’s MSP430F5418chip to realize the functions of MCU. A combination of contact and non-contact mode complete the IC card operation. Extending application module includes OLED display module, LED&buzzer, power supply module, tamper-proof structure, which aimed at improving the ability of human-computer interaction and endurance for OBU.RF part is composed of5.8GHz RF transceiver unit and antenna. The first CMOS SOC chip BK.5822meeting the China ETC standards chip complete data transceiver. A simple-structured notched-rectangular antenna fed by microstrip line, which can be connected with RF link easily, can realize right handed circularly polarized. As well as this part of paper tested the RF performance.Finally, the design of OBU was realized which can communicate with the RSU successfully. In order to test the performance of the OBU, this paper tested environmental adaptability and the results are all up to nation standards.