The Implementation And Research Of The Hard Real-Time RATI Based On An ARM9 Processor

With the extensive application of embedded systems, the embedded Real-Time Operating Sytstem(RTOS) also becomes more and more important, especially in the industrial control, aerospace, medical sanitation and military fields. RTAI (Real-Time Application Interface) is an open source project following the GPL initially developed by the Dipartimento di Ingeneria Aerospaziale, Politecnico di Milano(DIAPM). It is a hard real-time extension to Linux kernel and it provides industrial-grade RTOS functions, which can be accessed in GNU/Linux environment. Now there are many applications based on RTAI, such as RTnet, USB4RT, RTCAN and so on. RTAI is continually developing and more and more applied in real-time environment, so it has a broad prospect.Based on the above meanings, this dissertation first explains some concepts of real-time operating system. Conclude the elements affecting the capability of real-time system by respectively analyzing the relative concepts including task scheduling, interrupt response time, memory management, etc. And talk about several real-time Linux architectures at present. Then we research the RTAI implementation mechanisms based on ARM architecture, especially the principle and implementation of ADEOS/IPIPE nano-kenel based on Linux on this platform.The design of the hardware platform is based on AT91RM9200 processor. AT91RM9200 is a microprocessor based on ARM920T core by ATMEL used in system control and communications, which integrates USB, Ethernet, EBI, MCI, SSC, SPI and some other rich peripheral interfaces. The high processing speed and advanced power management make the chip be used in many fields. As the most important part of this design is to transplant Linux/RTAI to the development board based on AT91RM9200 and to test the real-time capability, the memory(Flash and SDRAM) is necessary. The JTAG is uesd in downloading and debugging programs, and serial port can be used to print debug information to facilitate the application development. The Ethernet port can communicate with PC in a high speed. The other interfaces are optional and with wire leaded to extend applications.The design transplants the Bootloader, Linux kernel, root file system and RTAI to the hardware platform. The versions are respectively u-boot 1.3.4, Linux 2.6.20 and RTAI 3.7. They can run at the hardware platform well. Finally, we make the task time resolution test and task response speed test between RTAI and traditional Linux on the hardware and software platform. By Analyzing the real-time performance between RTAI and Linux, it provides a guidance and reference for real-time application development.