Study On RTOS Based On System On Chip For Media Application

The development of chip design and semiconductor technique makes the system integrated into a chip possible.The embedded system design goes to System-on-Chip(SoC) era.Meanwhile, media application development requires more processing ability.Multiprocessors system on one chip(MPSOC) is a trend for media application due to its powerful processing ability,low power consumption and flexibility.Because real-time operating systems can screen the details of hardware,improve the portability and reusability of application,improve the stability of system and reduce the time that chip goes to the market,it becomes one of the most important part of software system of SoC.The author takes part in software research work for MediaSoC3221A and high performance MPSoC,named MediaSoC64x that developed by SoC R&D group of information and electronics engineering department of Zhejiang University.The author is responsible for embedded RTOS design.This paper is based on the RTOS Iota.The author enhances the Iota function and develops it to new edition.The work that RTOS kernel design based on task management,an object oriented scheduling that supported MPSoC programming and the debug function realization based on RTOS for MPSoC is included in this paper.This paper carries on the work that Iota running in Media-SoC firstly.For MPEG-1 decoding system,this paper divides application into several tasks,analyzes the characteristic of these tasks and gives the task management scheduling realization that based on RTOS.Although the task management of RTOS increases system overhead,it simplifies the application programmer work greatly.The MPSoC MediaSoC64x under developing is mainly for high performance media application,such as MPEG-4,H.264.Iota is not fit for MPSoC and system overhead will large under more tasks.According to characteristic of media application,this paper presents new scheduling model that different from task management,namely an object oriented model scheduling.An object oriented model scheduling assigns each object into processors of MPSoC according to coarse grain data flow graph(CGDFG).The connection relationship between objects is registered in RTOS during its initialization process.The directors hosted on every processor manage the objects according to their connection relation and make the processors work together to finish the data flow process.This scheduling model supports MPSoC programming.It has the characteristics of low system overhead,small code and flexibility.The advent of heterogeneous MPSoC causes more difficulty tbr debug function realization. This paper compromises the factors of develop time and realization cost.and presents software implementation method of debug function based on RTOS.For making sure RTOS correctness. debug work of RTOS is carried out firstly.This part utilizes the hardware module EJTAG support and software project named RDView is developed.The debug management module of RTOS can realize the debug function of MPSoC after RTOS is debugged right.The debug management module of RTOS is comprised of three parts,debug command set part,the interface between human and computer for command input and result output part and execution command module part.The debug process in RTOS realizes data synchronization and transmission between command input part and execution command part.The execution command part hosted on different processors can execute debug command to realize debug function for MPSoC.