Research On Technology Of USB & CPLD And Application In Measurement And Control Systems

As a part of measurement and control systems, the interfaces play an important part of the information transmission and processing, such as the transmission-mode, the transmission-speed and the code-format of information and the logic levels. In the measurement and control system based on the PC, the interfaces are mainly PCI bus or ISA bus. Sometimes RS-232 bus and parallel ports are also used. But these interfaces have many disadvantages. Firstly, they are fussier to setup, more to cost and slower to transmit. Secondly, they are not plug and play and can not be shared. Most importantly, they are restricted to the number of slot, address and interrupt resources in computers.USB, called universal serial bus, is a new computer interface bus. And it has been developed to the USB2.0, which is plug and play, faster to transmit, easier to be connected, less to cost and to power itself etc. As the result of its many merits, it has been widely applied in many fields such as printers, scanners, digital cameras, industrial cameras, MP3 and mobile hard disks.To realize the special logic function, the complex programmable logic device (CPLD) allows programmers to program and configure the triggers and logic gates inside. The logic program of CPLD can be modified again and again, so it's not only more flexible and more competitive, but also can meet many special and individual designs. For its less periods to be developed, less cost to be invested, no risk, less area of PCB, the high reliability of system, easier to be modified, less cost in the small production and many other merits, CPLD has been applied to digital systems.To overcome the disadvantages of traditional interfaces, the thesis has...