智能数字万用表的设计 指导教师：湖北师范学院电工电子实验教学中心竞赛指导小组 队员及年级：陈永刚、高熙、胡刚【2006级】 学校及院系：湖北师范学院物理与电子信息学院 摘要：本设计能够精确的测量直流电压、交流电压和电阻，具有测量精度高，抗干扰 能力强等特点。整个系统可以用一块9V电池供电，实现了低功耗和便携功能。小电阻测量是 采用独立恒流供电端口四端子测量法，从而减小了接触电阻的影响，实现了小电阻高精度测 量；交流测量是用AD637真有效值转换芯片将交流信号转换成直流电压后测量；用带钳位保护 的反向放大器进行输入电压转换，实现了10MΩ的输入阻抗和高安全性。电路中关键器件采用 TI公司的精密运算放大器OPA07和仪表放大器INA128，实现了高精度的测量；ADC采用MC14433 芯片；控制器选用TI公司的MSP430单片机，实现了低功耗，量程自动切换功能。另外，通过 利用和改装波段开关，实现了测量档位转换的便捷和可靠。该作品的所有性能指标远远超出 题目的设计要求。 关键词：数字万用表、MC14433、MSP430单片机 Abstract: The design has the function of measuring DC voltage, AC voltage and resistance. The system supplied by the 9V battery has the advantages of high accuracy, strong anti-interference ability, low power consumption, being portable and so on. In order to measure small resistance accurately, the system gets the voltage signal of the resistance through the measure port independent of the constant current power supply port and eliminates the influence of the contact resistance. The measurement of AC voltage adopts the chip AD637, which is a complete high accuracy monolithic rms-to-dc converter. The system realizes the 10M? input im