AN4827 ATmegaS128 IO Expander

Microchip Technology Inc.

Published Date: 09-Feb-2023


This application note describes the implementation of a Radiation Tolerant Port Expander application using the Serial Peripheral Interface (SPI) interface on the ATmegaS family of space-qualified AVR Microcontrollers (MCUs). The goal is to functionally emulate the MCP23S17. The ATmegaS128 is a function and pin-identical variant of the ATmega128 commercial device, and it ensures a full code and toolchain compatibility.