【应用笔记】使用MAX II和MAX3000A器件扩展微控制器I/O口(Using MAX II & MAX 3000A Devices as a Microcontroller I/O Expander) Many microcontroller and microprocessors limit I/O ports and pins to conserve pin counts and reduce package sizes. For many microcontroller- (e.g., PIC, 8051, and SX) or microprocessor-based systems, the system design requires more I/O pins without changing the microcontroller. To increase the number of I/O pins without changing the microcontroller, I/O expansion provides a solution. With up to 272 I/O pins and MultiVoltTM I/O capability, Altera® MAX® II and MAX 3000A devices allow you to implement microcontroller I/O expansion in microcontroller- or microprocessor based systems. This application note explains how to implement a microcontroller I/O expander in MAX II and MAX 3000A devices. Using MAX II & MAX 3000A Devices as a Microcontroller I/O Expander March 2004, ver 2.0 Application Note 265 Introduction Many microcontroller and microprocessors limit I/O ports and pins to conserve pin counts and reduce package sizes. For many microcontroller- (e.g., PIC, 8051, and SX) or microprocessor-based systems, the system design requires more I/O pins without changing the microcontroller. To increase the number of I/O p……