Development Of Wireless Sensor Network General Nodes

Sensor technology, micro-electromechanical system, modern network and wireless communication technology are integrated into the Wireless Sensor Network(WSN). The WSN, which is constructed of massive miniature sensors deployed in the monitoring region, is a self-organizing network using the wireless jumps relaying way conmmunication. The WSN expands people's ability of accessing to information, and makes the physical information of the objective world and the transmission network together, which provides people with real information of most direct and effective. So it has a very broad application prospect. With the different applications, the WSN has different hardware platforms, software systems and network protocols. Thus, the nodes system must have good generality, transportability, and low developing difficulty to meet the different requirements. And the embedded real-time operating system can solve this problem well.In this thesis, using an embedded real-time operating system based on PIC24 family microprocessor which is developed by Microchip company as the software platform, a WSN general nodes system is designed, which has the characteristics of generality, transportability and expandability.Firstly, the source code of the embedded real-time operating system is studied, and the optimization about the message mechanism is put forward.Secondly, because of the internal flash program memory's special read and write performance of the PIC24 family microprocessor, an optimized scheme about the memory management is developed in the operating system, which contributes to operate the flash program memory.Thirdly, based on the optimized embedded real-time operating system, the WSN general nodes system is established, which is conbination of the WSN architecture and the task and message mechanism of the operating system. Referring to the WSN protocol satck, adopting layered srtucture design, the designed WSN system is aim for shielding the software realization of each layer and providing interfaces for them.Finally, taking two projects as examples, the convenient and efficient programming based on the WSN general nodes system platform is illustrated by giving the detailed software code.The successful running of the two projects shows that the designed WSN general nodes system is of good stability and reliability. It is observed that developing WSN system based on the embedded real-time operating system can greatly reduces the difficulty of designing application program, accelerates development speed, lowers the cost and enhances the system's stability, reliability, transportability and expandability effectively.