The 51 Minimum System with School Emblem

A CH340C microcontroller was used to implement a USB-to-serial converter, eliminating the need for an external programmer and facilitating program debugging.
The 3V output used an XC6206P332MR linear regulator in a compact SOT-23 package.
The LED module used a 0805 package with a 1K current-limiting resistor.
The motor driver used an L9110S, which is inexpensive and has a large current drive capability, handling 800mA of continuous current per channel and up to 5A of peak current.
The buzzer driver used an S8050NPN transistor. Since the buzzer is an inductive component, the current cannot suddenly drop to zero when it stops working, so a 1N5819WS Zener diode was connected in parallel as a release path. An
89C52 microcontroller was used as the main controller, employing a 12MHz crystal oscillator. Without a crystal oscillator, there is no timing cycle, and without a timing cycle, the code cannot be executed; therefore, the crystal oscillator is crucial for the microcontroller. A high-level signal to the RST pin of the microcontroller will automatically reset the system. The P0 port does not have a built-in pull-up resistor; an external pull-up resistor is required.