The Design And Development Of Real Time Operation System Base On Arm Processor

With the development of embedded system, more and more projects use real time operating system (RTOS) as their development platform. At present the developers need not only an effective RTOS kernel, but a RTOS which includes huge hardware platform supports and system modules directly. According to this real demand, we developed a RTOS named KEOS (Keep it Easy Operation System) in this paper.The kernel KEOS supports 32 task priority levels and each task priority can have more than one task. General used kernel objects are implemented, which include semaphore, mutual exclusion semaphore, semaphore set, message box and data queue; an optimized timing wheel is used in timer service and a method based on fixed size dynamic memory allocation from system free pages is implemented for memory allocation service.Based on the kernel of KEOS we designed a unified driver interface, porting and simplying virtual file system under Linux. And Microsoft's FAT file system is also realized under the virtual file system. So developers who want to get file system support on KEOS only need to write their lower hardware driver codes.KEOS is ported to hardware platform based on ARM9 processor. When KEOS is porting to other hardware platforms and more system modules are imported, the code files greatly increase in numbers. We use GNU make for code management and modelers configuration, by adding the simple and flexible Makefile script under every KEOS source code directory, we can make the source code files which are used by different compilers and different hardware platform keep in one source code tree. So we can conveniently support more hardware platforms and modules for users.