Using MAX II & MAX 3000A Devices as a Microcontroller IO 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.