This design is a minimum system based on ATMEGA32U4 microcontroller (leonardo minimum system) .

ATMEGA32U4 microcontroller is a more commonly used keyboard and mouse simulation chip, which can be used to develop custom keyboard and mouse, and can also be carried out like Arduino Micro series Development. 

This design mainly includes power supply circuit, crystal oscillator circuit, reset circuit, programming interface, micro data transmission circuit, and other peripheral auxiliary circuits. 

And all available interfaces are led out to facilitate development and design. 

This design is compatible with the Arduino Micro series development board, can achieve most of the functions, can develop a series of keyboards and mice, such as the commonly used 104-key keyboard, customized high-quality GH60 keyboard, and can also develop relatively unpopular arrangements, such as 96 Key, 87 key, 75 key, 64 key keyboard, etc. 

You can also customize the keyboard layout for development, and easy to program. 

The smaller size allows you to be more bold when developing!