STC8G_PWM three-speed adjustable exhaust fan

Three-speed PWM speed-adjustable exhaust fan designed based on STC8G1K08A microcontroller:
 
 
The device leads to a button and USB interface. The button is used to switch the fan on and off and adjust the three-speed speed. The USB port can be connected to external devices such as LED lights.
The device uses two external power supply methods, Type-C and Usb-A, choose one.
The device uses a 5V 40*40*10mm fan.
 
Three-speed speed regulation: Use the PCA function of the microcontroller to put it in the pwm working state, and obtain the speed regulation function by controlling the ratio of the output high and low levels. In the program of this project, I only define three pwm gears, each of which is 100 % high, 80% high, 60% high, change the pwm gear and switch control through buttons.
 
 
To use this project, you need to understand the programming of STC microcontroller. The programming interface has been led out:
VIN: 3.3V-5V
 
 
Shell model: Due to personal technical reasons and poor printer debugging, the printing effect of my model is not satisfactory. I have provided this The shell model is in the attachment, please use it as a reference. It should be enlarged to 102-103% when printing, and there is no back cover. . .