INTRODUCTION
GPIO expanders provide easy I/O expansion using standard serial interfaces. GPIO products are used to increase the I/O on an MCU or provide remote I/O using a serial interface.
This application note discusses the feature set and use of the MCP23X08/17 (8-bit and 16-bit) GPIO Expanders.

FEATURES
This application note discusses some of the features of the MCP23X08/17 and how they may be used in an application:
• I/O Port Description
• 8/16-Bit Mode (MCP23X17 only)
• Interrupt Features
    - Mapping Interrupts
    - Mirroring Interrupts (MCP23X17 only)
    - Servicing Interrupts
• Internal Address Pointer Control
• Hardware Address Pin on SPI