Migration And Improving Of FreeRTOS For Water Quality Monitoring Wireless Sensor Network

The development of Wireless Sensor Network (WSN) and water qualitymonitoring is reviewedin this paper,firstly. Been studyedfor the current microoperating system, memory managing technology and the ion concentrationmeasurement technology in water quality monitoring application, the mainresearchworkin this paper is schemed: design a wireless sensor network hardwareplatform for water quality monitoring, micro operating systemwith performance oflow-power consumption, real-time task operation in WSN, analysize and verificationfor the RF connectivity, power comsumption and real-time performance of thesystem.As for hardwaredesign, the CPU ofLM3S8962with Ethernet control block,which is the ARM Cortex-M3series, is selected. ADS1244, which theAnalog-to-Digital Converter ocupied with single channel and24bits resolution, isapplied fordata acquisition; LTC3555, which is controlled through I2C Bus for thethree output voltages, the power manage ASICis usedfor the dynamic voltageadjustable. And,the RF transceiver module with CC1100which its power and wirlesschannel can program through SPI Busisembedded in WSN nodes.Software structure model of5layers,pHysical layer, hardware abstraction layer(HAL), RTOS kernel, application interface layer and application layer, respectively,isconstructedin software design routine. Firstly, the board support package (BSP) iscompletedfor dataacquisition, wireless transceiver, power managing, and Ethernetcommunication interface through the configuration and debug for relative regiestersin specified hardware. Been analyzingfor the event-driven framework of FreeRTOS, aconclusion is drawn that FreeRTOS could be used in WSN. In order to improveFreeRTOS, CPU can enter the sleep status after the IDLE task routine is executed. Asa result, FreeRTOS can be added up to low-power consumption in WSN. Combiningwith the original FreeRTOS program designing ways, the speical program designingmethod with FreeRTOSis made out inthis paper. After finding out the shortage of memory management of FreeRTOS, two-level segregated fit (TLSF) for memoryallocator is aggregated to FreeRTOS to improve the efficiency and reliableness ofmemory allocating and releasing. Finnally, Light-weightIP protocol stack of lwIP isapplied for the ability of communication so thatEhternet, remote control anddata-acquisition can be implemented easily.During the cource of research, the accomplishmenthas several points as follow:Mote design(LM3S8962+CC1100+LTC3555) for water quality monitoringwireless sensor network, the higher-precision ion concentration data acquisition, themicro operating system for wireless sensor network by FreeRTOS adding CPUsleeping mode to it, and the resource codes packaging of user API. Finnaly,connectivenesscheck, test for design function and verification for performance arefinished.