[Guangdong University of Technology] Simple waveform amplifier and measurement display

Use discrete components, capacitors, resistors and transistors to design a three-stage amplification circuit, and use push-pull output to increase the potential through resistor division to facilitate microcontroller ADC measurement. The stm32 microcontroller processes the data and draws the waveform through the LCD screen and displays each data. (1) The common emission of the first stage is used to ensure normal signal amplification. (2) The second stage common collector is directly coupled to the first stage, and the input and output impedances of the front and rear common emitter stages are adjusted so that the common emitter output of the latter stage can also have an amplification factor that meets the requirements. (3) The third-level common emission achieves top distortion and bottom distortion by adjusting the operating point. (4) The last stage is push-pull output, and the voltage output node is adjusted to 0-3.3V to adapt to the measurement range of the microcontroller.

Afterwards, the I/O port corresponding to channel 11 of the microcontroller ADC1 is PC1, and the ADC1_GPIO_Config() function is used to configure the PC1 port to collect voltage. We configure the ADC to trigger the ADC interrupt using a timer and configure the TIM2 in output PWM mode, triggered by the TIM2_CC2 input capture.We use STM32 4.3-inch LCD to display waveforms in real time. At the same time, pressing KEY0 and KEY2 can adjust the pulse width of the waveform. The keys KEY1 and KEY_UP can move the yellow cursor left and right to measure the voltage at a certain point of the waveform.