The Research And Implement Of An Temprature Measuring System Based On USB Host

USB(Universal Serial Bus)came forth in 1995, and have become a standard solution in establishing the link between PC and peripheral equipments. Because of extremely extensive application of it, USB is attracted to apply in embedded system for expanding the system bus to link with the peripheral equipments. But in most applications, USB equipments are used in the slave(peripheral)moder linked to the PC as the peripheral equipment. And it also need USB equipments to work in the host mode with the hand-in devices' development. Most of the traditional temperature measuring apparatus carried out the lineate long-distance data transfers by the way of RS485, which limited work place and portability of them, and can not satisfy the requirement of market.This dissertation researched and designed a new kind of temperature measuring system which based on the technique of USB HOST, and can carried out the function of communications and transmission portably. This dissertation discussed the chip configuration and constituting theories of USB HOST module, the new scheme of temperature data collection and convertion which based on DS18B20, and the exploitation of USB drive under the context of USB HOST.First of all, the article introduced the technique basic of USB, and summarize the exploitation technique of USB HOST. Secondly, it provided the collectivity design scheme of hardware of temperature measuring system, which used 89C52 as CPU, the new USB chip CH375 that had the function of USB HOST, to constitute the USB HOST module, and used DS18B20 of DALLAS to collect temperature data in multiway, convert the format of data and stored it temporarily, and then realize the enumeration and configuration to USB disk, and USB Bulk in, Bulk out transmmition that supported Mass Storage class, stored the temperature data into USB disk accordingly. For the sake of reflecting thework status of system, it communicated with PC by serial bus in the way of RS232.At last, the article provided the collectivity design scheme of software of system, parsed the design of the process of temperature data collection and convertion, Host Controller driver, USB Driver, device class driver and the process of FAT16 file system.