AVRUSB technology is the use of high performance 8 bit RISC architecture of the AVR microcontroller, the use of single-chip IO port to simulate the USB communication port, the software to achieve USB communication protocol, the general AVR microcontroller analog into a USB low speed device, so as to achieve the communication and control between AVR microcontroller and computer. The basic principle of AVRUSB technology is the use of AVR microcontroller IO port to simulate the USB hardware port for communication. Because the speed of the low speed USB device is 1.5M bits / second, while the AVR microcontroller is a single instruction cycle, the 12MHz clock frequency in the single chip microcomputer, it is 8 times 1.5MHz. In that way, the single chip microcomputer 8 instructions to complete a data bit. 　　With this method, the time series of the single chip microcomputer is very strict, so the core of the software is written in assembly language.