Based On Acoral Operating System Device Driver Model And The Design And Implementation Of A Usb Device Driver

With the continuous development of the embedded technology,many embededoperating systems are also emerging. More and more embedded system solutions haveused Linux and WinCE in the non-real-time domain, but in the real-time domain,VxWorks and other open-source systems have occupied the market. Now, thedevelopment of open source real-time kernels is very flourishing, aCoral that ourproject team have developed independently and released its source code, is targeting ina hard real-time circumstance. It has supportted the FAT file system, a lightweightTCP/IP protocol stack and the GUI.The development of electronic technology makes peripheral’s types continues togrow. Driver as the underlying charge of the communication between peripheral andprocess, its complexity is also rising. Therefore, to make aCoral more robust andmultifunctional so that it can be widely used, we will need to write more drivers for it,meanwhile, to design a device driver framework. Device driver framework makes thehierarchy of the system clearer and the driver development to be able to follow theuniform rules in order to save the development cycle.Through the analysis of common operating systems’ device driver models, we cansee the way their own strengths, but the design idea and purpose is to decompose thecomplexity of the driver through the use of hierarchical structure and make the driver’sbug isolated with the kernel. Combined with aCoral kernel’s own characteristics, Idesign and implement a device driver framework for aCoral in order to ensure that thedriver model to minimize the impact real-time kernel and to control the complexity ofthe system.Taking the versatility of the USB bus into account, this paper introduces the USBand the EHCI specification, but also the implementation of the USB protocol stack andthe host drivers which can be used to test the availability and versatility of theframework.