Virtuelle Java-Maschinen für kleine eingebettete Systeme

Java is an object oriented programming language. But mainly because of the costs it’s not widely used on embedded systems. Typical Java virtual machines require larger systems. This work aims for integration of Java on inexpensive 8-bit microcontrollers. This makes Java possible in the world of measurement, control and automation and allows the combination of control, user interaction and communication on a single system. E. g. Java can be used to enable home automation with less programming effort. To integrate Java on small embedded systems with low memory consumption, some techniques are explored and realized on a microcontroller (ST7). Due to preprocessing of Java programs and the virtual machine itself on a development system, the program memory allocation on the target system is reduced. Applicable data structures and class libraries (API) are designed to use as little data memory as possible. If Java bytecode is combined with the target system’s native code, peripheral components can be utilized. Furthermore deadline based thread scheduling can be used for time critical tasks. Together with a software environment for development systems this results in an operative Java system on a microcontroller. Experiences developing this JavaVM are now resulting to new development practices for creation of specialized embedded virtual machines. A completely Java based multilayered model is able to match various target systems. The model contains the virtual machine (kernel and runtime) and a generic application programming interface. Only at the end, code generators insert target system specific native code into the model.