Port Extension Technique Research of PIC Microcontroller Based on I2C Bus Tan Ping1, Liu Jian-xin2 ( 1. School of Mathematical &Computer Science, Xihua University; 2. School of Mechanical Engineering & Automation, Xihua University, Sichuan,Chengdu,610039,China) [Abstract] In order to extend the port of an embedded system with PIC18F458, which mainly controls the display of automotive body status, the ZLG7290 is introduced. The principle of I2C, involved register control of PIC18F458, hardware configuration and rule of software development are emphasized. [key word] I2C Bus Embedded System PIC18F458 ZLG7290