In summary, GPIO expanders are a simple, cost-effective way to monitor and control several peripheral signals that come from a microcontroller. NXP offers many options for GPIO expanders, including: Quasi, Totem-Pole and Open Drain, which were explained in this presentation. Additionally, NXP offers a new generation of I/O Expanders called Agile I/O. Finally, there are a number of demonstration boards and support channels available for engineers to get started or assist in the development process.