Research And Application Of WebCam Control System Based On RTSJ

With the wide usage in the fields of Automation, Transportation Electronics and Consumer Electronics, Embedded Systems have developed rapidly in recent years. At the same time, as the size and complexity of Embedded Systems becoming bigger, the traditional development language, for example, C language and even assemble language, can not control the growing complexity well any more. And the efficiency of development and reusability of traditional development methods are very low. Consequently we need new development method and means. Because of the excellent Object-oriented feature, rich APIs, reusability, rapid development and security, Java becomes the preferred solution to the problem.Most of embedded systems are real-time systems, which are strict with the determinacy and deadline of the program. However, some properties of Java, such as the garbage collection mechanism, dynamic class loading and dynamic code compilation and so on, have become the main obstacles of its application in the real-time systems development. To solve this problem, Real Time Specification for Java is prompted.This paper researches the improved mechanisms to traditional Java given by RTSJ, such as RealtimeThread, ImmortalMemory, ScopedMemory, Asynchronous Transfer of Control and so on. After researching and using RTSJ and analyzing the Ravenscar-Java real-time program model, this paper removes some restrictions of the program model, especially those about using ScopedMemory. And adds a regulation that several threads could start from a ScopedMemory to share it and in other situations the share of ScopedMemory between threads is forbidden, some other modifications are also made. After the modification developer could use ScopedMemory more flexibly and the program model could be used to make a better guidance to soft real-time system programming.Considering the real demand of an embedded company, this paper designs and implements a USB WebCam control program. This paper develops a control program using Java firstly, without using RTSJ. Throuth the test it is found that the program can't meet the real-time demand. The paper gives a detailed analysis to the existing real-time problems. And then this paper implements a USB WebCam control program based on RTSJ and the improved real-time program model. The control program is developed on Linux and runs on TimeSys company's real-time JVM-RI. The control program uses V4L2 to access and control the WebCam. The other technique used includes JNI and SDLJava. The control program's function includes capturing video from WebCam, receiving user's commands to save video files, shoot pictures and adjust the attributes of the WebCam, such as contrast, brightness, WebCam's angle and so on. At last a test is done to the control program; it shows that the control program based on RTSJ could meet the real-time demand.