Beginning with the principle of the USI and I~2C, taking Attiny26 as example, which belongs to AVR series, this article describes how to achieve the master mode and slave mode of I~2C by USI, and introduces how to write and read the EEPROM in master mode.

• 从USI(通用串行接口)及I2C的工作原理出发,以AVR系列Attiny26为例,详细的阐述了如何采用USI实现I2C的主机模式和从机模式,并简要介绍了如何利用Mastermode对EEPROM进行读写。