Researching And Designing Of A Versatile Low Power WSN System

Wireless sensor network is a small self-organized regional digital low-power wireless data transmitting network, with advantages of low cost and easy to maintain. However, due to the wireless channel environment is complex, affected by environmental constraints hardware platform is battery-powered, single wireless band and high power consumption of devices limit the actual promotion of this technology. The commonly used software systems for wireless sensor networks also exists problems such as the underlying code is not open source, micro operating systems have poor real-time task scheduling methods, available target hardware range is small and difficult to transplant.To solve the above problems, a new versatile low power wireless sensor network hardware platform is designed. This platform can work with any of mainstream wireless RF modules to suit a variety of different channel environments. A corresponding modular blocked software system designed for this platform is developed; programmers can build up their custom application according to their requiring.A model of IAP15F (L) 2K61S2 microcomputer produced by STC is selected to build up the new platform. The chip has a program code storage space of 61 KB and a SRAM data space of 2KB for coding, it has on-chip IAP and ISP function, C51 and 8031 assemble programming language is supported. In order to use any kind of wireless block, a versatile wireless block interface is designed for adapting. For more future uses, a hardware external interface is provided on the platform. After all hardware designing works, two main figure:wireless data transmitting distance and power consumption are tested, the distance of data sending can reach 150 meter; power cost is as low as 280 mw, they can reach the requirement of the project.The software system consists of three parts:hardware devices drivers, a independent developed micro-kernel real-time WSNOS and a common protocol program. Many hardware driver programs are integrated in the modular soft system; users can call them in upper level programs. The independent developed WSNOS contains task stacks, task scheduler and dispatching controller etc. A real-time scheduling called "time-slice rotation scheduler" which is widely used in general computer OS and sequence scheduling in traditional WSNOS are all designed in the new WSNOS, and providing a control interface for users via the function code for upper level programs, users can use them to finish system initial and tasks dispatching easily. The wireless data transfer protocol program is a two level protocol called EZMac, the program can adapt 64 bytes data frame, and it can be used on some kind wireless blocks after alteration.All above works are completed and debugging, the hardware platforms and software systems are in good working condition, wireless data can transported stable, power consumption is low, new micro-kernel WSNOS can dispatching tasks in a higher performance way than sequence schedule methods obviously when tasks long run and can dispatch complex algorithm programs; protocol program effectively prevent packet collisions can use wireless networking features profiles. A practical WSNs can implement after connecting corresponding sensor devices and the host computer.