stm32f103c6t6 minimum system board

The hardware
    circuit uses LM358 for amplification and is powered by 5V DC power supply. Since the ADC of the microcontroller cannot collect negative values, we add a DC bias of 1/2Vcc to the signal, and the gain is adjustable by 50 times.
 
Originally planned to be made into a patch, but the test signal amplification is very poor, the signal interference is very strong, and the knowledge is limited. I can't figure out why. In the end, it was made into a plug-in.
 
The stm32f103c6t6 minimum system board contains the external low-speed clock of the RTC. If downloading No For problems with target connected or Internal command error, you need to hold down the reset button before downloading, and then release the reset button while downloading.
Detailed operation reference: Guess the cause and solution of No target connected or Internal command error in self-made stm32F103c6t6
 
Software
reference: The music spectrum production of stm32f103+FFT+OLED
is transplanted into a 4-pin IIC protocol 0.96-inch OLED, and it is common to stm32f103c8t6 and c6t6 . The amplification frequency program is adjustable.
 
The pin interface can be established in the form of a HAL library by modifying the program framework through OLED.h.
 
If you have not learned it, you may be a little confused about
 
the HAL configuration and program reference of ADC sampling: HAL library (STM32CubeMX) - ADC learning summary
 
 
renderings