Design And Implementation Of A Low-power Online Water Quality Monitoring System Based On CC2640

Water shortage and water pollution is one of the main environmental problems in the country,which makes it necessary to monitor the environmental water quality.In this paper,low power quality online monitoring system is designed,mainly composed of battery module,sensor module,CC2640 control module and BLE data receiving module,including the realization of pH value,TDS value(or conductivity)and water temperature measurement in the water.The main contents of this paper include:In order to solve the problem of on-line maintenance of pH electrode,which exists in the process of pH measurement,this paper presents a method of online slope calibration based on Nernst equation.It solves the problem that the pH electrode’s difficulty on-line calibration because of the constraint of system structure,and the experimental results show that this method can meet the system design requirements.Also in the pH measurement,the low-pass FIR filter is designed to meet the requirements of high resolution sampling and high precision measurement.For the TDS(or conductivity)measurement,this paper proposes a new TDS measurement method based on unipolar excitation.By changing the design of TDS measuring circuit,this method eliminates the differential between the negative and positive power supply and simplifies the circuit design,and the measurement results show that the method can meet the requirement of system measurement.Based on the CC2640 ultra low power chip,the low power design of the online water quality monitoring system is completed from the software and hardware design.The hardware designing implements the power management for time-sharing power supply,based on the low-power software architecture of CC2640,the software designing completes the design of low power driver and application program,and finally obtained the result of low power consumption test.In summary,the system designed in this paper can meet the requirements of water quality monitoring,and can also meet the demand of long time working in the battery powered system.Through further improvement,the system can be used as a new option for on-line water quality monitoring.