Development Of A Transistor Graphing Instrument Based On STM32

The traditional transistor tracer has the advantages of large volume,single measurement parameters,high manufacturing cost and few types of measurable transistors.In this paper,a digital transistor tracer based on STM32 is developed.It has many kinds of measuring transistors,rich measuring curves and low manufacturing cost.It can be used as an experimental teaching equipment for enterprise production test and electronic information specialty in Colleges and universities.The hardware circuit of the transistor tracer adopts modular design,and the STM32F103RCT6 microcontroller is used as the main control unit.According to the measurement principle of transistor characteristic curve,the step voltage,step current and scan voltage generating circuits for measuring the transistor input and output characteristic curve are designed,and the measurement of transistor pin current and inter electrode voltage is completed.The production of transistor measurement signal is based on KEIL integrated development environment.Through STM32 microcontroller and I~2C bus control,digital quantity is generated to DAC.After DAC transformation,ladder voltage signal and scanning voltage signal are generated.After differential amplification and V-I conversion circuit,they are added to the transistor to be tested.The current and voltage on the transistor are measured by the measuring circuit,and then sent to the 16bit high-precision ADC through the instrument amplifier and voltage follower to obtain the digital measurement results.The measurement results are calculated and processed by STM32 microcontroller,and the measured curves and characteristic parameters are displayed by LCD and saved by external memory for easy reference.It can be used to measure the characteristic curves of medium and small power diodes,triodes and MOSFETs.It can also display the parameters of transistor on voltage,triode common emitter current amplification factor and triode inter electrode through current.The resolution current is 15?A.The resolution voltage is 7.6m V.A digital transistor tracer with high precision,low cost and rich measurement types is realized.