Research Of Communication Technology On Vehicle Traveling Data Recorder

Embedded system is a fast developing new field.RS232,CAN and USB have been developing rapidly in the field of electronic equipment, having the attributes of low-cost,rapid-speed,ease-of-extend,so they are applied widely.Therefore,the realization of RS232,CAN and USB communication functions in embedded system has the practical significance and the application prospect.As a real-time monitoring electronic product,Vehicle Traveling Data Recorder saves the important information of the running state of a car.It will provide reliable and correct information,which is helpful for the analysis of accidents.Based on the requirements of "National Standard of Vehicle Travelling Data Recorder"(GB/T 19056-2003) and special communication demand of FCEV,an Vehicle Traveling Data Recorder consists of RS232,CAN and USB communication modules were researched.The USB module has two functions—USB Host/USB Slave, and the two functions can be switched between each other.Using RS232 interface is for the communication between VTDR and PC or other serial devices(such as a printer).Adding CAN interface is used for getting data from CAN bus.In order to get rid of PC for storing collected data and to improve the speed of data transporting,a USB Host/Slave interface is designed.The host function could identify a U disk and store the collected data from CAN interface into the U disk.The slave function allows a PC to identify and support the USB interface module and to communicate with the VTDR by much more higher transporting speed as a USB device.This paper focus on the researching of basal configuration,working principle,hardware and software for the three interfaces and deeply analyses some special aspects of the USB interface module,such as the theory of USB interface,the enumeration of a USB equipment to the USB Host for identification,USB Mass Storage class specification of a mass storage removable device,construction of FAT file system,how a USB Host can use Bulk-Only transfer protocol to read/write the data on the USB flash disk by sending USB Floppy Interface(UFI) commands,and introducing three programs for realizing USB Slave function which are USB controller driver program,core driver program and user software.In the end,an experiment is carried out and reveals that the operation of this system is steady and the functions such as high rate data collecting,reliable transmission and processing are well fulfilled.