Pseudo-real-time control of a USB I/O device under Windows 7

Windows-based PCs (Personal Computers) provide a powerful development environment for controller synthesis because it is easy to evaluate the control effect via installed multifunction I/O devices. These I/O devices are expensive due to handling a real-time processing while non-real-time I/O devices are constructed by inexpensive generalpurpose ICs (Integrated Circuits.) The aim of this paper is to assemble an inexpensive I/O device with USB interface and to realize a software-based real-time processing. Since Windows does not allow application programs to access such devices, device drivers are required certainly. Device driver should be coded by fulfilling the device drivers' specification but it is so costly for beginners. The present paper relaxes the development cost by employing the KMDF (Kernel-Mode Driver Framework.) Then the authors develop an application program to command the I/O device periodically. In order to measure the elapsed time precisely, the paper utilizes the RDTSC (Read Time Stamp Counter) instruction. The authors tackle the stabilization problem of the rotational inverted pendulum to evaluate the usefulness of the developed system.