Design Of Electrochemical Measurement Instrument Based On Embedded System

Electrochemical measurement technique is important means and testing technology forstudying on the electrode and regulation during electrochemical reactions, and it get wideattention and application in these fields such as chemical, medical, environmental, biological,sensors and so on. But electrochemical reaction process is so complex that Ohm’s law is nottrue, the electrode potential is difficult to control accurately, detection has many errors. In thisarticle, constitute upper and lower computer core based on C8051F020microcontroller andS3C2440processor respectively, and design electrochemical measurement scheme based onembedded system, resolving electrochemical measurement problem for portable applications.Thesis designs lower computer measurement and control circuit based on C8051F020,including waveform generator circuit which provides scanning voltage, constant-voltagecircuit which controls electrode potentials accurately, micro-current detection circuit whichdetects reaction current, microcontroller interface and peripheral circuit. Waveform generatorcircuit provides scan voltage site value for±1.2V and resolution which is less than1mV,using12bit DAC. Constant potential circuit guarantees working electrode potential stabilitywith respect to reference electrode, using combination of precision amplifier OP07.Measurement current resolution of microcurrent detection circuit is less than1nA and it has6species measurement sensitivity, using precision amplifier LMC6482and analog switchMAX4781. Micro-controller is core of hardware, which combines other parts into a wholeusing its interrupt service.In order to achieve "embedded", thesis builts software platform for embedded systems,analysis and retransplants the bootloader and Linux kernel, makes root file system, and builda graphical user interface system based on the QT/Embedded, providing the basis for runningfor the application.Thesis designs electrochemical measurement instrument software, including the lowercomputer programs bases on C language and the upper computer applications based on Qt.The former receives experimental parameters and status control commands, acquires experim-ent data, controls waveform output, and sends experiment data using serial port receivedoverflow interrupt, timer2,3,4overlow interrupt, ADC sampling data interrupt. The latter has some function such as communication settings, parameter settings, real-time waveformdrawing and historical features, providing good human-machine interface to users.This system is designed based on “embedded”, and it has small size and can achieveelectrochemical measurement by two basic electrochemical measuring method such as cyclicvoltammetry and Chronoamperometry. It uses powerful microprocessor and programs withmodular, convenient to add function, providing a good foundation for further more detailedstudy.