The Study, Based On The ¦Ìc/os- ¢ò Kernel Device Driver Framework

With the development of software and hardware technology in embedded system, more and more embedded systems have adopted embedded operation system for more complicated application and development. The embedded system has been applied in wide fields, of which most are medium-sized or mini-type systems. For these systems, operation systems like VxWorks, WinCE or Embedded Linux either cost too much or have too complex structure. In this situation, it's a better selection to use the open source software—μC/OS-II as the kernel of the embedded system since it bears small scale, good real-time performance and low cost. However, it's a pity that theμC/OS-II itself has no device management component which is very important in the development of embedded system. Although, later on, the developer of theμC/OS-II has provided series of device driver likeμCGUI,μCFS,μCIP,μCFLASH, these drivers focus on universality without close link with the kernel and all the device drivers are not free. Under this condition, this paper will try to construct a feasible device drive frame so that when developing drive programmes, developers could be guided and save time.Through researches on some popular operation systems, we know that they all have strict device management mechanism. The developers, with these platforms, only need to focus on the logic of the device itself and complete the functions required by the device drive frame, without considering the relation between the device and the kernel.On broad sense, the device driver consists of two parts, namely, dependent part(low-level driver) and independent part(high-level driver). This paper will study the building of the two parts in the kernel ofμC/OS-II respectively. As to the low-level driver, how to design and implement the device management frame and interrupt service management frame will be included. With regard to high-level driver, the study will mainly focus on two kinds of drivers: network protocol stack and graphic user interface(GUI). And we will conduct a deep discussion on the construction of high-level drive via self-dependent development or transplant.Considering the more and more popular application of file system in the embedded system, the last part of the paper will mainly analyze YAFFS, which is a file system designed for NAND Flash and an approach of transplanting it to the kernel ofμC/OS-II will be provided in detail.