51 microcontroller minimum system board ( )

I. Schematic Design
As you can see, the schematic is actually quite simple.

The C52 main controller is the minimum system that allows a 51 microcontroller to function, with all I/O ports brought out using headers. It doesn't cover some other learning modules.
Power and serial ports are reserved to provide power for external modules. The system board doesn't include a CH340 download circuit, and this would increase the difficulty of PCB design; many people omit this for their first time.
Indicator Lights: Three indicator lights for power, RXD, and TXD.
Reset Button: Restarts the program.
Modules: This system board has three modules: a running light, an independent button, and a traffic light. Other learning modules will be designed as smaller modules for ease of use.

II. PCB Design

For a learning system board, what's most important? Silkscreen, of course! Otherwise, you'd have to look up the corresponding I/O ports on the schematic every time you write a program. Silkscreen placement is crucial in PCB design.
Component layout is also extremely important; they should be arranged logically and appropriately divided into zones for a cleaner look.
Pay attention to the width of power and signal lines when routing traces.