Simple Oscilloscope

Physical demonstration!
Note: This project is a secondary
development of the charging and discharging circuit based on the Hardwood Classroom open-source project (https://oshwhub.com/damihuang/AFE03).
The charging and discharging chip uses the IP5306, which supports direct USB 5V charging and directly boosts the battery discharge voltage to 5V, making it very convenient to use. Four external LEDs can indicate the battery's charging and discharging capacity.
Analog input channel introduction:
Includes signal conditioning implemented with resistor voltage dividers and operational amplifiers, and a square wave output implemented with a comparator (for triggering and frequency measurement).
INA, INB: Oscilloscope input terminals. The pocket instrument sends an analog signal to this point. Here, a 1MΩ input impedance is achieved through a series resistor voltage divider, generating two selectable signals: one with 1/8 attenuation and the other with 1/40 attenuation.
Gain: A selector switch that chooses a signal attenuated by 1/8 or 1/40 to enter the first-stage non-inverting amplifier. The non-inverting amplifier performs two functions: first, it amplifies the input signal at the non-inverting input by a factor of two; second, it shifts the amplified signal by 1.65V, calculated as Vo = 1.65 + 2*Vi. Therefore, the overall gain of the corresponding circuit is 1/4 or 1/10.
AnalogA, AnalogB: The amplified and shifted analog signals are connected to the STM32H750 development board and enter the H750's ADC.
TrigerA, TrigerB: The square wave signals generated by AnalogA, AnalogB, and the DC reference level (generated by one of the H750's DACs) after passing through a comparator, enter the STM32H750's timer for frequency measurement.
DAC_OUT2: The DC reference level, output through the STM32H750's internal DAC2 configuration.
 
Analog Output Channel Introduction:
This includes signal conditioning implemented with resistor voltage dividers and operational amplifiers, and a square wave output implemented with a comparator (for triggering and frequency measurement).
The STM32H750's DAC1 output ranges from 0-3.3V.
A second-order RC filter implements a low-pass filter function.
A resistor voltage divider and buffer convert the 5V input to a low-impedance 2V output, which is then amplified by -5 times for signal shifting.
The output amplifier performs two functions: first, it amplifies the non-inverting input by 6 times; second, it shifts the amplified signal by 6 times to -10V before outputting it, calculated as Vo = -10 + 6 * Vi.
A voltage divider network is used to achieve better results when outputting small signals using analog voltage division.
 
 
 
 
 
Comparator Circuit:
To implement triggering and frequency meter functions, we designed two comparator channels on the board. These channels convert the waveforms from the two analog input channels before they enter the ADC into square wave signals for use as timer inputs for the H750. The reason for using the waveform before it enters the ADC for comparison is that the waveform entering the ADC has been conditioned by the front-end analog circuitry to fall within the known 0-3.3V range, making the comparator's comparison threshold easier to design.
As shown in the diagram above, the H750 uses its internal DAC2 to output a 0-3.3V DC signal to compare with the waveform of channel 2 before it enters the ADC, converting the waveform of channel 2 into a square wave. This allows the H750's timer function to use the square wave signal for interrupt handling and timer capture processing.