#JALCIC Training Camp# [1712472A] #Simple Digital Oscilloscope

I. System Board Selection:
The main control board used is the LCSC GD32e230c8t6 minimum system board. I bought two, one of which was a free gift with a coupon. At the time, boards were in short supply, so I didn't rush to replicate the project. I waited for the official development board release, partly because I hadn't used GigaDevice chips before and wanted to try them out.
 
II. Main Circuits:
1. Analog Front-End Processing Circuit:
The analog front-end processing circuit includes both DC and AC coupling modes, switched via switch SW2. In DC coupling, a 100nF capacitor blocks the DC component.
Switch SW3 selects whether to attenuate the input signal; the attenuation circuit uses a resistor divider to reduce the voltage to 1/50 of the original signal.
The two operational amplifiers, TL072IP, act as a voltage follower and a proportional amplifier, respectively. The input signal first passes through the voltage follower, utilizing its high input impedance and low output impedance for impedance matching, before being converted by the proportional amplifier. The proportional amplifier circuit outputs Vo = (5 − Vin) / 2. The voltage range of the ADC acquired by the microcontroller is 0~3.3V. With 1/50 attenuation, the measurement range is approximately -80V~250V; without attenuation, the measurement range is approximately -1.6V~5V.
2. Comparator frequency measurement circuit:
3. Negative voltage generation circuit
: This circuit generates a -5V voltage to provide a -5V voltage to the analog front-end processing circuit.
III. Other circuits:
The USB power input circuit provides voltage and current to the entire circuit; a 1.8-inch TFT screen, with an ST7735 main controller, uses SPI communication to display waveforms and some oscilloscope parameters; a rotary encoder controls waveform scaling and pause; three buttons are used for PWM output frequency adjustment, duty cycle adjustment, and PWM generation switch, respectively.
IV. Finished Product Display