CW32 Simple Voltage and Current Meter

I'd always heard about the high accuracy of the CW32
's ADC, but I'd never had the chance to use it. I even missed the training camp organized by the CW32 ecosystem community. Thanks to LCSC EDA and the CW32 ecosystem community for providing the 1 RMB development board and other coupons, and for organizing this training camp, they taught us how to build a voltage and current meter step-by-step.
On the hardware side

, this voltage and current meter offers two voltage division ratios for measuring voltage,
provides four sockets for comparative testing and calibration with multimeters and other measuring tools,
uses a 100 milliohm resistor for voltage sampling, calculates and measures current,
increases current routing, and supports high current input.

On the software side

, it supports switching ADC sampling pins to change ranges,
switching reference voltages to change accuracy and calibration, and
calibration to adjust measured values .

During the construction process
, I followed the teacher's schematics step-by-step, learning a lot of key technical knowledge and PCB design skills
, but I still encountered many pitfalls, including accidentally drawing the board incorrectly. After soldering, the power indicator light didn't turn on when plugged into a DC power supply, but it did work when plugged into a USB port. After much research and testing with a multimeter, I finally found the problem. I had drawn the diode at the DC power input position backwards, preventing power from flowing. I removed the diode, reversed its orientation, and the problem was fixed.
The schematic has also been corrected.
Below is a picture of the actual circuit .