A LIGHTWEIGHT OPERATING SYSTEM FOR DYNAMIC WIRELESS APPLICATION DEVELOPMENT KIT TO INCREASE USABLE MEMORY

Abstract

A replaceable scheduler is provided to support different scheduling policies that meet the requirements of different WSN applications. The efficiency of the scheduler is improved by fast algorithms instead of linear search for the next running thread; the overhead of context switch can also be reduced by storing the critical registers on the internal stack and avoiding using the slow external memory. The proposed approach for overcoming resource constraints is compiler-assisted run-time support for features such as virtual memory, remote reprogramming and memory allocation. Virtual memory can be achieved without hardware support via code insertion at compile time. Position-independent code (PIC) is a suitable approach to achieving dynamic loading; the compiler can assist with the generation of PIC on the host PC, thus avoiding the overhead of relocating addresses at run-time. With the host PC’s help, the run-time overhead on the wireless sensor nodes can be reduced significantly. Flash File System has been developed to achieve efficient file operation and low power consumption. To minimize the active time of the MMC card by I/O scheduling and by limiting the access via the API is provided by Flash File System. To reduce code size, it is proposed to let the controller can handle wear levelling and erase-before-write.