基于PIC单片机的pH测试仪

Design of pH Measure Instrument Based on PIC Single-chip Microcomputer

设计了一种酸碱浓度(pH)测试仪,介绍了测量仪的设计原理、硬件电路及软件设计。选用高精度差动放大器INA116放大复合电极输出的微弱电压信号、抑制现场干扰及复合电极的高内阻影响。为满足测量精度,对温度信号进行了有效补偿并通过软件校正电极偏差。PIC单片机进行实时处理。测试仪具有两点标定、自动温度补偿等功能。测试结果表明:测试仪能准确地测量溶液的pH值,满足设计要求。具有精度高、稳定性好、操作便捷等优点,应用前景广阔。

An acidity measure instrument was designed.The design principles,hardware circuit and software designs were introduced.The high-precision differential amplifier,INA116,amplified the weak voltage signal from the composite electrodes.The effects of field interference and high inner resistance of the composite electrodes were suppressed.In order to meet the measure accuracy,the temperature signal was compensated,and the electrode deviation was calibrated by software.The PIC single-chip microcomputer processed the date real-timely.The instrument has the functions of two-point calibration,auto temperature compensation and historical data storage.The test results show that the instrument can measure the pH value of the solutions accurately,it meets the design requirements.The instrument has the advantages of high precision,good stability and convenient operation,and possesses broad application prospects.